Juvenile literature 164 Science -- 98 Mathematics -- 80 Encyclopedia 52 Education -- 50 Study guides 46 Textbooks 46 more ... Chemistry -- 44 Physics -- 44 Encyclopedias 43 Biology -- 42 Curricula 42 Examinations -- 40 Mathematics 36 Animals -- 34 Plants -- 34 juvenile literature 34 Birds -- 31 Science 28 Biology 27 Physics 27 Dictionaries 26 encyclopedias 24 Languages 23 Research 22 Study and teaching 21 Zoology -- 21 study and teaching 21 Chemistry 20 Juvenile Litreature 20 less ...