This paper by a leading Soviet theoretical physical geographer traces the historical development of the Soviet doctrine of geographic zonality and the role played by heat-moisture relationships in determining the structure, the dynamics and the development of natural geographic zones. The paper includes a table of geographic zonality and explains the periodic character of geographic zonality. Am American review article that provides useful background is: Jacek I. Romanowski, A Survey of Heat and Water Balance Research in the Soviet Union, University of Washington, Discussion Paper No. 41.