The Belgian/French bunker research group Belfra has released some PDFs on their finds about the different Tobruk types. I host the English translations as a mirror to the forum http://lemurdelatlantique.lebonforum.com/.
Have fun with these docs and thanks to the Belfra group. Also take a look at http://forum.axishistory.com/viewforum.php?f=70 for discussions on the findings.
This page will be updated with new documents so you can bookmark this page.
Regelbau L 479 Part 1 (English)
Regelbau L 479 Part 2 (English)
Feldflugplatz Coquelles Part 1 (English)