The remote island of Rapa Nui is known as Easter Island thanks to Dutch explorer Jacob Roggeveen, who christened the name when he came upon the secluded spot in the South Pacific on Easter Sunday in 1722.
Many travel guides simply include a section on the island (and its famous mysterious moai statues) in their books that cover Chile. One of the more recently updated guides containing information on Easter Island is the Moon Guide to Chile. The second edition of this book was released in January 2007 and is written by Wayne Bernhardson, who has been traveling to Chile since 1979.
Whatever resources you use to research a visit, be sure to thumb through several Chile guides to compare their Easter Island sections. A good starting point right on the web is the Easter Island Foundation, a handy and well-organized online guide to the history, culture and people of Easter Island. Their Ideal Easter Island Bookshelf is an excellent place to look for additional book resources.