Influences of Geographic Environment On the Basis of Ratzel's System of Anthropo-Geography

The Earth as Modified by Human Action

Man and Nature; Or, Physical Geography as Modified by Human Action

The Theory of Environment An Outline of the History of the Idea of Milieu, and Its Present Status, part 1

Mensch und Erde: Skizzen von den Wechselbeziehungen zwischen beiden

Psychological Aspects of the Problem of Atmospheric Smoke Pollution