Loomis, Grace Hubbard. Windsor’s Heritage: 1633-1967. Warehouse Point, CT: Woodworth Press, 1967.
Loomis’ book is about the history of Windsor and its settlement. The author, although perhaps incorrectly stating that the natives of this area acted particularly violently, does discuss native population and disease.
Cooper, Karen Coody. They Have Seized Upon Our Country: The Wangunk of Wethersfield. n.d.
Although Cooper does not specifically discuss the Massacoe, she shares a history of the Connecticut River Valley natives. The author’s most relevant points deal with disease at the time of native-settler contact, and its toll on the native population. Cooper finds her information from letters, journals, reports, etc.