De Prins en Johan de Witt
Prins Alphabet
Principles of Teaching
The Principles of Success in Literature
The Principles of Stratigraphical Geology
The Principles of Secularism
The Principles of Scientific Management
Principles of Public Health
Principles of Political Economy
Principles of Mining: Valuation, Organization and Administration
The Principles of Language-Study
Principles of Home Decoration, With Practical Examples
Principles of Freedom
The Principles of Economics, with Applications to Practical Problems
Principles of Decorative Design
The Principles of Chemistry, Volume II