Where do I get a newer DOS?

[mmettler@ttmath.ttu.edu (Michael J. Mettler)]

I recently acquired a couple of Apple //c machines along with some
circa 1984 software, including the original System Utilities, which
have ProDos 1.0.2 on them.  Browsing through robot.asimov.net, I've
found master disk images (.DSK files) for Dos 3.3 and ProDos 4.2.
I'd like to get these (I assume) newer DOSs into a form usable by
the //c, but am not sure how to proceed.  Any suggestions?

Thanks.
-- 
Michael J. Mettler     | Proud (?) owner of a 486DX2-80, a 386DX40,        |
mmettler@math.ttu.edu  | two 'turbo' XTs,  1 IBM XT, 3 IBM PCs, a Mac      |
math grad. student :-/ | 512K, an Apple //c, an Atari 400, and a TI99/4A   |