SUBJECT
Science
1,457
Study and teaching
1,283
Mathematics
936
Study and teaching (Elementary)
563
Chemistry
535
Juvenile literature
479
Physics
463
Biology
454
Study and teaching (Secondary)
436
Congresses
360
Education
305
Experiments
218
Laboratory manuals
167
History
165
Algebra
139
Arithmetic
134
Handbooks, manuals, etc
128
Problems, exercises, etc
126
Teaching
121
Ecology
119
Addresses, essays, lectures
118
Chemistry, Organic
117
Research
116
Astronomy
108
Training of
101
Curricula
100
Technology
98
Dictionaries
95
Teachers
87
Statistics
86
Curriculum planning
85
Calculus
84
English language
84
Human ecology
84
Botany
79
Biography
78
Social aspects
78
Evaluation
76
Philosophy
72
Geometry
71
Pollution
71
Science teachers
70
Environmental education
69
Problems, questions, exercises
68
Genetics
67
Study and teaching (Higher)
65
Problem solving
63
Study and teaching (Primary)
63
Psychology
60
Earth sciences
59
more ...