Collected works History 17 Chemistry, Organic 11 Philosophy 10 Mathematics 9 Addresses, essays, lectures 6 Composite materials 6 Physiology 6 Chemical tests and reagents 5 Synthesis 5 Alkaloids 4 History and criticism 4 Sleep 4 Communism 3 Drugs 3 Historiography 3 Learning, Psychology of 3 Literature 3 Nuclear magnetic resonance spectroscopy 3 Proteins 3 Social aspects 3 Social conditions 3 Social psychology 3 Stress (Physiology) 3 Stress (Psychology) 3 Biochemistry 2 Biological chemistry 2 Carbon 2 Chemistry, Physical organic 2 Civilization 2