His books Smolensk under Soviet Rule, based on documents captured by the German Army during World War II, and How Russia is Ruled (also known as How the Soviet Union is Governed) helped form the basis of American study of the Soviet Union, and established him "as a leading political scientist of the Soviet Union."
Bukunya Smolensk under Soviet Rule, yang berdasarkan pada dokumen-dokumen yang direbut oleh Angkatan Darat Jerman pada Perang Dunia II, dan How Russia is Ruled (juga dikenal sebagai How the Soviet Union is Governed) membantu membentuk dasar kajian Amerika terhadap Uni Soviet, dan menjadikannya "ilmuwan politik utama dari Uni Soviet."