Query on vowel mergers

[Laurence Horn]

An undergraduate student here, James Sumner, is looking for
references to work on the classic merger of front lax vowels before
nasals in Southern States English, e.g. neutralization of the
distinction in "pin"/"pen".   Are there standard reference books or
articles on this, treating the class of nasals (other than /n/)
licensing the merger, and whatever other variables might be involved?
James is also curious about the [gIt] pronunciation of "get", which
is presumably a case of lexical diffusion (no [bIt] for "bet" or
[mIt] for "met").

Please send all responses to <james.sumner at yale.edu> as well as to the list.

Thanks.

--larry