UDC简表(=) * 4(Vacant; linguistics transferred to 81) *5 Mathematics and natural sciences x 54 Chemistry Crystallography. Mineralogy 6 Applied sciences. Medicine. Technology x 62 Engineering. Technology in general *7 The arts. Recreation. Entertainment Sport *8 Language Linguistics Literature 9 Geography. Biography. HistoryUDC简表（二）  4 (Vacant; linguistics transferred to 81)  5 Mathematics and natural sciences  54 Chemistry. Crystallography. Mineralogy  6 Applied sciences. Medicine. Technology  62 Engineering. Technology in general  7 The arts. Recreation. Entertainment. Sport  8 Language. Linguistics. Literature  9 Geography. Biography. History