540 - Chemistry & allied sciences 620 - Engineering & allied operations 64 600 - Technology 63 500 - Natural sciences & mathematics 9 363 - Other social problems & services 8 700 - The arts; fine & decorative arts 4 610 - Medicine & health 3 414 - Phonology & phonetics 2 551 - Geology, hydrology & meteorology 2 574 - [Unassigned] 2 581 - Specific topics in natural history 2 000 - Computer science, information & general works 1 140 - Specific philosophical schools 1 380 - Commerce, communications & transportation 1 547 - Organic chemistry 1