He received his doctorate at the University of London in 1950 for a thesis on crowd action during the French Revolution.

He received his PhD for a thesis on Georges Bataille, eventually published as his first book.

He continued his studies in economics, receiving his master's degree in 1961 for a thesis arguing that foreign investment damaged a country's economic development.

In 1859, he received his doctorate in Kiel for a thesis on epilepsy and urinary secretions.

He received his doctorate in 1960 for a thesis on the British Mandate of Palestine.

He received his PhD from Edinburgh in 1972 for a thesis on university liberalism and democracy, 1860-1886.

He received his PhD in 1994 for a thesis discussing the Chinese economy during the Ming Dynasty.

Traveling to India to study the country's religions, in 1933 he received his PhD for a thesis devoted to a discussion of Yoga.

He received a Ph.D. degree in 1930 for a thesis on latent cyclical components in time series.

He received his Ph.D. in April 1930 for a thesis on alternative algebras.