900 - History & geography 620 - Engineering & allied operations 34 320 - Political science 22 330 - Economics 21 600 - Technology 19 363 - Other social problems & services 12 380 - Commerce, communications & transportation 5 700 - The arts; fine & decorative arts 4 000 - Computer science, information & general works 3 100 - Philosophy & psychology 3 301 - Sociology & anthropology 3 300 - Social sciences 2 340 - Law 2 500 - Natural sciences & mathematics 2 610 - Medicine & health 2 140 - Specific philosophical schools 1 170 - Ethics 1 200 - Religion 1 370 - Education 1 400 - Language 1 520 - Astronomy & allied sciences 1 530 - Physics 1 581 - Specific topics in natural history 1 630 - Agriculture & related technologies 1 780 - Music 1