Academic sources on the historicity of the 12 apostles

Can anyone provide any references to good academic sources that thoroughly analyze the evidence for and against the historicity of the 12 apostles as a designated group chosen personally by Jesus? (For anyone who's interested, the reasoning behind my own negative opinion so far can be found in my public post history from Sep. 30.) I am interested in sources that treat material such as the canonical gospels as one set of historical sources among others, rather than granting them credence by default.

Thanks!