basic books on modernization theory

I have a student doing an independent study course on modernization. Basically, what I need is the titles of two or three books on modernization theory that explains it in simple terms. The student is not a sociology major and does not have a strong background in sociological theory. This is meant to be a basic, introductory course, and readability is an especially important aspect of these books. So, if anyone can give me a few ideas, that would be helpful. Feel free to e-mail me privately.\