Book Description from Wikipedia:
Political Man: The Social Bases of Politics is an award winning political science book by Seymour Martin Lipset. The book is an influential analysis of the bases of democracy across the world. One of the important sections is Chapters 2: "Economic Development and Democracy." Larry Diamond and Gary Marks argue "Lipset's assertion of a direct relationship between economic development and democracy has been subjected to extensive empirical examination, both quantitative and qualitative, in the past 30 years. And the evidence shows, with striking clarity and consistency, a strong causal relationship between economic development and democracy."
Excerpt from the book concerning "political legitimacy":