Here are some articles from llli.org about relactation and adoptive breastfeeding.
I would like to resume breastfeeding after an interruption. How do I relactate?
Back to the Breast
My Newborn has never really gotten the hang of nursing. How can I get him back to the breast?
When a baby won't nurse
Helping a mother whose baby is reluctant to nurse (technical information, good to share with your healthcare provider)
Can I Breastfeed My Adopted Baby?
Adoptive Breastfeeding Beyond Infancy
Phoebe's Journey (relactation to breastfeed an adopted child)
Breastfeeding an adopted baby and relactation are possible!
A collection of New Beginnings Articles on Adoptive Breastfeeding