Websites
APLB The Association For Pet Loss And Bereavement is a non-profit organization that puts out a quarterly newsletter for members. Their site also has a chatroom, an "In Memoriam" section, hotline numbers & more.
Books
Blessing the Bridge: What Animals Teach Us About Death, Dying , and Beyond by Rita M. Reynolds
For Every Dog an Angel by Christine Davis
Talking With the Animals by Patty Summers