Being Adopted: The Lifelong Search for Self, by David Brodzinsky
Making Room in Our Hearts: Keeping Family Ties Through Open Adoption, by Micky Duxbury
The Primal Wound: Understanding the Adopted Child, by Nancy Verrier
In Their Voices: Black Americans on Transracial Adoption by Rhonda M. Roorda
Inside Transracial Adoption by Beth Hall and Gail Steinberg
Creole Son: An Adoptive Mother Untangles Nature and Nurture, by E. Kay Trimberger
Kids Books
Sam's Sister by Juliet C. Bond (This is the only children's book I know of that is directed toward the children of a birth family, helping them understand that there is an adoption plan for the baby their mother is currently carrying. It is an excellent description of the open adoption placement process in general.)
Tell Me Again About the Night I Was Born by Jamie Lee Curtis