http://www.amazon.com/s/ref=ntt_at_ep_srch?ie=UTF8&search-alias=books&field-author=Donald+H+Sullivan&sort=relevancerank
However "Boriken" is now available in both ebook and paperback at Riverok Books.
www.lulu.com/spotlight/dhsully
"Boriken" is a historical novella about the people of pre-Columbian Puerto Rico, and Boriken was the name given to the island by the Taino before the arrival of Columbus.