SUBJECT
Science
1,268
Study and teaching
1,015
Mathematics
859
Chemistry
481
Physics
435
Biology
429
Juvenile literature
413
Study and teaching (Elementary)
413
Study and teaching (Secondary)
341
Experiments
209
Congresses
164
Laboratory manuals
162
Algebra
132
Arithmetic
131
Chemistry, Organic
115
Problems, exercises, etc
110
Astronomy
107
Ecology
101
History
89
Calculus
84
Botany
76
Biography
72
Problems, questions, exercises
68
Geometry
67
Genetics
66
Technology
64
Earth sciences
59
Science teachers
55
Handbooks, manuals, etc
53
Addresses, essays, lectures
52
Earth
51
Study and teaching (Primary)
51
Dictionaries
49
Juvenile works
49
Geology
48
Philosophy
45
Social aspects
44
Activity programs
43
Research
41
Study and teaching (Higher)
41
Training of
39
Problem solving
38
Statistics
38
Electricity
35
Popular works
33
Biochemistry
32
Chemistry, Physical and theoretical
32
Physical sciences
32
Plants
32
Evaluation
31
more ...