The following books are really good resources for people who are seeking to learn more about polyamory. These are the books that I most often recommend to people who are poly-curious, who are trying polyamory for the first time, or who are interested in opening up an existing monogamous relationship. Experienced polyamorists may pick up some tips from these books, also.
The Ethical Slut: A Practical Guide to Polyamory, Open Relationships & Other Adventures, by Dossie Easton and Janet Hardy
Opening Up: A Guide to Creating and Sustaining Open Relationships, by Tristan Taormino
More Than Two: A Practical Guide to Ethical Polyamory, by Franklin Veaux and Eve Rickert