I know I've got some web-links somewhere but I'm afraid can't find 'em now.

One source of info I'd heartily recommend is Neil Short's recent 'Tank Turret Fortifications' book. Very full coverage of all sorts of temporary and permanent mounts, both officially designed and extemporised around the world, from complete buried tanks to strange wooden constructions(though some German panzers still emplaced on the Bulgarian border seem to have passed his attention). It's a little dry to read but with the lack of other good info it's immediately become a handy standard work.

I'll have another look for those links, I'm sure there's quite good coverage of Panther turret fortifications along the Gothic line.

Here's one emplacement on top of a coastal bunker that I snapped in Jersey last year:

Cheers,
Adam.