00265nam a2200109 a 450000500170000008200160001710000110003324500400004426000240008430000260010863000210013420251202164222.0  a001.42bCLA  aGaul W  aClassification as atool of research  aHolandbNorthc1986  aXIII, 502, 24 cm>cHB  aResearch methods