Classification
577 - Ecology
1,860
333 - Economics of land & energy
1,588
363 - Other social problems & services
1,017
581 - Specific topics in natural history
740
551 - Geology, hydrology & meteorology
695
580 - Plants (Botany)
632
330 - Economics
546
630 - Agriculture & related technologies
504
304 - Factors affecting social behavior
481
579 - Microorganisms, fungi & algae
421
571 - Physiology & related subjects
374
576 - Genetics & evolution
373
700 - The arts; fine & decorative arts
347
000 - Computer science, information & general works
336
910 - Geography & travel
327
610 - Medicine & health
319
620 - Engineering & allied operations
319
600 - Technology
306
570 - Life sciences; biology
295
320 - Political science
290
616 - Diseases
254
900 - History & geography
245
590 - Animals (Zoology)
223
500 - Natural sciences & mathematics
210
338 - Production
205
140 - Specific philosophical schools
199
300 - Social sciences
195
572 - Biochemistry
187
550 - Earth sciences
181
658 - General management
180
660 - Chemical engineering
167
370 - Education
161
634 - Orchards, fruits & forestry
154
301 - Sociology & anthropology
134
631 - Techniques, equipment & materials
130
380 - Commerce, communications & transportation
118
100 - Philosophy & psychology
116
591 - Specific topics in natural history
115
621 - Applied physics
114
628 - Sanitary & municipal engineering
113
519 - Probabilities & applied mathematics
112
006 - Special computer methods
104
578 - Natural history of organisms
98
004 - Data processing & computer science
96
612 - Human physiology
91
720 - Architecture
87
306 - Culture & institutions
84
592 - Invertebrates
83
540 - Chemistry & allied sciences
79
005 - Computer programming, programs & data
73
more ...