Fra i due mondi

Civilization and Beyond: Learning from History

The Land of Contrasts: A Briton's View of His American Kin

Manhood of Humanity.

What I Saw in America

The American Mind The E. T. Earl Lectures

Modern Society

The Spirit of America

Prehistoric man

The Future in America: A Search After Realities

Primitive culture, vol. 2 (of 2)

L'évolution actuelle du monde: illusions et réalités