Harold H. Kelley 
Personal Relationships [PDF ebook] 
Their Structures and Processes

First published in 1982. This book summarizes certain concepts and evidence regarding the nature of close personal relationships. Its purpose is to suggest how such relationships are to be conceptualized for scientific analysis. What are the essential properties of a personal relationship? What are its necessary defining structures and processes? The material presented herein represents what Kelley has thought and learned about the social psychology of close relationships.