The Yoruba-Speaking Peoples of the Slave Coast of West Africa (1894) is an important work of in-depth research into one of the principal indigenous communities of West Africa and examines their religion, customs, laws and language, and contains an extensive appendix comparing the Tshi (Oji), Ga, Ewe and Yoruba languages.

The first comprehensive history of German youth in WWI, this book investigates the dawn of the great era of mobilizing teenagers and schoolchildren for experiments in state-building and extreme political movements like fascism and communism.