The standard textbook for studying language contact, as far as I know, was Language Contact, Creolization, and Genetic Linguistics, by Sarah Grey Thomason & Terrence Kaufman, UCP (1991, c1988). The reader will surely recognize many of this text’s proposals of language contacts in my books.
Here are some relevant excerpts from the Introduction/Summary of chapter 1 (emphasis mine, some stylistic changes for clarity):
… Read the rest “Basic framework of language contact-induced change”
The starting point for our theory of linguistic interference is this: it is the sociolinguistic history of the speakers, and not the structure of their language, that is the primary determinant of the linguistic outcome