Search (461 results, page 2 of 24)

  • × theme_ss:"Suchmaschinen"
  1. Reischl, G.: ¬Die Google-Falle : die unkontrollierte Weltmacht im Internet (2008) 0.02 
    0.022961916 = product of:
  0.045923833 = sum of:
    0.045923833 = sum of:
      0.01537617 = weight(_text_:h in 2616) [ClassicSimilarity], result of:
        0.01537617 = score(doc=2616,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.16469726 = fieldWeight in 2616, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.046875 = fieldNorm(doc=2616)
      0.030547662 = weight(_text_:22 in 2616) [ClassicSimilarity], result of:
        0.030547662 = score(doc=2616,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.23214069 = fieldWeight in 2616, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.046875 = fieldNorm(doc=2616)
  0.5 = coord(1/2)
    Date
    7. 4.2008 21:22:57
    Footnote
    Vgl. auch: cw: Die Google-Falle. In: CD-Info. 2008, H.8, S.60-61.
  2. Fischer, T.; Neuroth, H.: SSG-FI - special subject gateways to high quality Internet resources for scientific users (2000) 0.02 
    0.022961916 = product of:
  0.045923833 = sum of:
    0.045923833 = sum of:
      0.01537617 = weight(_text_:h in 4873) [ClassicSimilarity], result of:
        0.01537617 = score(doc=4873,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.16469726 = fieldWeight in 4873, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.046875 = fieldNorm(doc=4873)
      0.030547662 = weight(_text_:22 in 4873) [ClassicSimilarity], result of:
        0.030547662 = score(doc=4873,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.23214069 = fieldWeight in 4873, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.046875 = fieldNorm(doc=4873)
  0.5 = coord(1/2)
    Date
    22. 6.2002 19:40:42
  3. Schultheiß, G.F.: Google, Goggle, Google, ... : Whose Mind is it Anywhere? Identifying and Meeting Divers User Needs in the Ongoing Sattle for Mindshare - NFAIS 47th Annual Conference, Philadelphia, USA vom 27. Februar bis 1. März 2005 (2005) 0.02 
    0.022961916 = product of:
  0.045923833 = sum of:
    0.045923833 = sum of:
      0.01537617 = weight(_text_:h in 3421) [ClassicSimilarity], result of:
        0.01537617 = score(doc=3421,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.16469726 = fieldWeight in 3421, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.046875 = fieldNorm(doc=3421)
      0.030547662 = weight(_text_:22 in 3421) [ClassicSimilarity], result of:
        0.030547662 = score(doc=3421,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.23214069 = fieldWeight in 3421, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.046875 = fieldNorm(doc=3421)
  0.5 = coord(1/2)
    Date
    22. 5.2005 13:38:26
    Source
    Information - Wissenschaft und Praxis. 56(2005) H.3, S.185-188
  4. Nicholson, S.; Sierra, T.; Eseryel, U.Y.; Park, J.-H.; Barkow, P.; Pozo, E.J.; Ward, J.: How much of it is real? : analysis of paid placement in Web search engine results (2006) 0.02 
    0.022961916 = product of:
  0.045923833 = sum of:
    0.045923833 = sum of:
      0.01537617 = weight(_text_:h in 5278) [ClassicSimilarity], result of:
        0.01537617 = score(doc=5278,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.16469726 = fieldWeight in 5278, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.046875 = fieldNorm(doc=5278)
      0.030547662 = weight(_text_:22 in 5278) [ClassicSimilarity], result of:
        0.030547662 = score(doc=5278,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.23214069 = fieldWeight in 5278, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.046875 = fieldNorm(doc=5278)
  0.5 = coord(1/2)
    Date
    22. 7.2006 16:32:57
  5. Alte Zeitschriften in Googles Buchsuche : Suchmaschine (2009) 0.02 
    0.022961916 = product of:
  0.045923833 = sum of:
    0.045923833 = sum of:
      0.01537617 = weight(_text_:h in 2619) [ClassicSimilarity], result of:
        0.01537617 = score(doc=2619,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.16469726 = fieldWeight in 2619, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.046875 = fieldNorm(doc=2619)
      0.030547662 = weight(_text_:22 in 2619) [ClassicSimilarity], result of:
        0.030547662 = score(doc=2619,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.23214069 = fieldWeight in 2619, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.046875 = fieldNorm(doc=2619)
  0.5 = coord(1/2)
    Date
    7. 2.2009 11:22:39
    Source
    Chip. 2009, H.2, S.37
  6. Lewandowski, D.: ¬Die Macht der Suchmaschinen und ihr Einfluss auf unsere Entscheidungen (2014) 0.02 
    0.022961916 = product of:
  0.045923833 = sum of:
    0.045923833 = sum of:
      0.01537617 = weight(_text_:h in 1491) [ClassicSimilarity], result of:
        0.01537617 = score(doc=1491,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.16469726 = fieldWeight in 1491, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.046875 = fieldNorm(doc=1491)
      0.030547662 = weight(_text_:22 in 1491) [ClassicSimilarity], result of:
        0.030547662 = score(doc=1491,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.23214069 = fieldWeight in 1491, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.046875 = fieldNorm(doc=1491)
  0.5 = coord(1/2)
    Date
    22. 9.2014 18:54:11
    Source
    Information - Wissenschaft und Praxis. 65(2014) H.4/5, S.231-238
  7. Großjohann, K.: Gathering-, Harvesting-, Suchmaschinen (1996) 0.02 
    0.02160046 = product of:
  0.04320092 = sum of:
    0.04320092 = product of:
      0.08640184 = sum of:
        0.08640184 = weight(_text_:22 in 3227) [ClassicSimilarity], result of:
          0.08640184 = score(doc=3227,freq=4.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.6565931 = fieldWeight in 3227, product of:
              2.0 = tf(freq=4.0), with freq of:
                4.0 = termFreq=4.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.09375 = fieldNorm(doc=3227)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    7. 2.1996 22:38:41
    Pages
    22 S
  8. Stock, M.; Stock, W.G.: Recherchieren im Internet (2004) 0.02 
    0.020365108 = product of:
  0.040730216 = sum of:
    0.040730216 = product of:
      0.08146043 = sum of:
        0.08146043 = weight(_text_:22 in 4686) [ClassicSimilarity], result of:
          0.08146043 = score(doc=4686,freq=2.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.61904186 = fieldWeight in 4686, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.125 = fieldNorm(doc=4686)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    27.11.2005 18:04:22
  9. Stock, W.G.: Qualitätskriterien von Suchmaschinen : Checkliste für Retrievalsysteme (2000) 0.02 
    0.019134931 = product of:
  0.038269863 = sum of:
    0.038269863 = sum of:
      0.012813476 = weight(_text_:h in 5773) [ClassicSimilarity], result of:
        0.012813476 = score(doc=5773,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.13724773 = fieldWeight in 5773, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.0390625 = fieldNorm(doc=5773)
      0.025456386 = weight(_text_:22 in 5773) [ClassicSimilarity], result of:
        0.025456386 = score(doc=5773,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.19345059 = fieldWeight in 5773, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.0390625 = fieldNorm(doc=5773)
  0.5 = coord(1/2)
    Source
    Password. 2000, H.5, S.22-31
  10. Faller, H.: David gegen Google : Wie ein Mathematiker aus New Jersey die größte Suchmaschine der Welt übertrumpfen will: Eine Reise ins Reich der Algorithmen (2004) 0.02 
    0.019134931 = product of:
  0.038269863 = sum of:
    0.038269863 = sum of:
      0.012813476 = weight(_text_:h in 2870) [ClassicSimilarity], result of:
        0.012813476 = score(doc=2870,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.13724773 = fieldWeight in 2870, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.0390625 = fieldNorm(doc=2870)
      0.025456386 = weight(_text_:22 in 2870) [ClassicSimilarity], result of:
        0.025456386 = score(doc=2870,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.19345059 = fieldWeight in 2870, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.0390625 = fieldNorm(doc=2870)
  0.5 = coord(1/2)
    Date
    15.10.2005 19:22:37
  11. Zutter, S.: Alles dreht sich um die Suche : Information Online Konferenz in Sydney, Australien (2005) 0.02 
    0.019134931 = product of:
  0.038269863 = sum of:
    0.038269863 = sum of:
      0.012813476 = weight(_text_:h in 3423) [ClassicSimilarity], result of:
        0.012813476 = score(doc=3423,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.13724773 = fieldWeight in 3423, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.0390625 = fieldNorm(doc=3423)
      0.025456386 = weight(_text_:22 in 3423) [ClassicSimilarity], result of:
        0.025456386 = score(doc=3423,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.19345059 = fieldWeight in 3423, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.0390625 = fieldNorm(doc=3423)
  0.5 = coord(1/2)
    Date
    22. 5.2005 13:51:43
    Source
    Information - Wissenschaft und Praxis. 56(2005) H.3, S.189-190
  12. Wikia Search : Das Anti-Google (2008) 0.02 
    0.019134931 = product of:
  0.038269863 = sum of:
    0.038269863 = sum of:
      0.012813476 = weight(_text_:h in 369) [ClassicSimilarity], result of:
        0.012813476 = score(doc=369,freq=2.0), product of:
          0.09336021 = queryWeight, product of:
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.03757783 = queryNorm
          0.13724773 = fieldWeight in 369, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            2.4844491 = idf(docFreq=10020, maxDocs=44218)
            0.0390625 = fieldNorm(doc=369)
      0.025456386 = weight(_text_:22 in 369) [ClassicSimilarity], result of:
        0.025456386 = score(doc=369,freq=2.0), product of:
          0.13159116 = queryWeight, product of:
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.03757783 = queryNorm
          0.19345059 = fieldWeight in 369, product of:
            1.4142135 = tf(freq=2.0), with freq of:
              2.0 = termFreq=2.0
            3.5018296 = idf(docFreq=3622, maxDocs=44218)
            0.0390625 = fieldNorm(doc=369)
  0.5 = coord(1/2)
    Source
    Chip. 2008, H.3, S.22
  13. MacLeod, R.: Promoting a subject gateway : a case study from EEVL (Edinburgh Engineering Virtual Library) (2000) 0.02 
    0.018000383 = product of:
  0.036000766 = sum of:
    0.036000766 = product of:
      0.07200153 = sum of:
        0.07200153 = weight(_text_:22 in 4872) [ClassicSimilarity], result of:
          0.07200153 = score(doc=4872,freq=4.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.54716086 = fieldWeight in 4872, product of:
              2.0 = tf(freq=4.0), with freq of:
                4.0 = termFreq=4.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.078125 = fieldNorm(doc=4872)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    22. 6.2002 19:40:22
  14. Vidmar, D.J.: Darwin on the Web : the evolution of search tools (1999) 0.02 
    0.01781947 = product of:
  0.03563894 = sum of:
    0.03563894 = product of:
      0.07127788 = sum of:
        0.07127788 = weight(_text_:22 in 3175) [ClassicSimilarity], result of:
          0.07127788 = score(doc=3175,freq=2.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.5416616 = fieldWeight in 3175, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.109375 = fieldNorm(doc=3175)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Source
    Computers in libraries. 19(1999) no.5, S.22-28
  15. Back, J.: ¬An evaluation of relevancy ranking techniques used by Internet search engines (2000) 0.02 
    0.01781947 = product of:
  0.03563894 = sum of:
    0.03563894 = product of:
      0.07127788 = sum of:
        0.07127788 = weight(_text_:22 in 3445) [ClassicSimilarity], result of:
          0.07127788 = score(doc=3445,freq=2.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.5416616 = fieldWeight in 3445, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.109375 = fieldNorm(doc=3445)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    25. 8.2005 17:42:22
  16. ap: Suchmaschinen in neuem Gewand : Metaspinner kennt 600 Millionen Seiten (1999) 0.02 
    0.01781947 = product of:
  0.03563894 = sum of:
    0.03563894 = product of:
      0.07127788 = sum of:
        0.07127788 = weight(_text_:22 in 4224) [ClassicSimilarity], result of:
          0.07127788 = score(doc=4224,freq=2.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.5416616 = fieldWeight in 4224, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.109375 = fieldNorm(doc=4224)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    3. 5.1997 8:44:22
  17. Dunning, A.: Do we still need search engines? (1999) 0.02 
    0.01781947 = product of:
  0.03563894 = sum of:
    0.03563894 = product of:
      0.07127788 = sum of:
        0.07127788 = weight(_text_:22 in 6021) [ClassicSimilarity], result of:
          0.07127788 = score(doc=6021,freq=2.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.5416616 = fieldWeight in 6021, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.109375 = fieldNorm(doc=6021)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Source
    Ariadne. 1999, no.22
  18. Bawden, D.: Google and the universe of knowledge (2008) 0.02 
    0.01781947 = product of:
  0.03563894 = sum of:
    0.03563894 = product of:
      0.07127788 = sum of:
        0.07127788 = weight(_text_:22 in 844) [ClassicSimilarity], result of:
          0.07127788 = score(doc=844,freq=2.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.5416616 = fieldWeight in 844, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.109375 = fieldNorm(doc=844)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    7. 6.2008 16:22:20
  19. Birmingham, J.: Internet search engines (1996) 0.02 
    0.015273831 = product of:
  0.030547662 = sum of:
    0.030547662 = product of:
      0.061095323 = sum of:
        0.061095323 = weight(_text_:22 in 5664) [ClassicSimilarity], result of:
          0.061095323 = score(doc=5664,freq=2.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.46428138 = fieldWeight in 5664, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.09375 = fieldNorm(doc=5664)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    10.11.1996 16:36:22
  20. Lob, S.: Per Mausklick auf die neusten Nachrichten : Internet-Suchmaschinen liefern Presse-Überblicke und stellen persönliche Zeitungen zusammen (1998) 0.02 
    0.015273831 = product of:
  0.030547662 = sum of:
    0.030547662 = product of:
      0.061095323 = sum of:
        0.061095323 = weight(_text_:22 in 1622) [ClassicSimilarity], result of:
          0.061095323 = score(doc=1622,freq=2.0), product of:
            0.13159116 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03757783 = queryNorm
            0.46428138 = fieldWeight in 1622, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.09375 = fieldNorm(doc=1622)
      0.5 = coord(1/2)
  0.5 = coord(1/2)
    Date
    29.12.1998 11:22:25

Authors

Years

Languages

  • d 336
  • e 122
  • nl 4
  • chi 1
  • f 1
  • More… Less…

Types

  • a 419
  • m 26
  • el 15
  • s 8
  • x 3
  • p 2
  • r 2
  • More… Less…

Themes

Subjects

Classifications