Literature on Greek Postal History (Part 2)

I checked Stampboards and found some posts dedicated on greek philately.

One concerns an identification of a cancelation :
http://stampboards.com/viewtopic.php?f=10&t=60966&hilit=greece

Another concerns a stamps for prostitutes?
http://stampboards.com/viewtopic.php?f=23&t=29235&hilit=greece

The last one is the most interesting one as it's related to perforation varieties for the 1990 Prefecture definitives series :
http://stampboards.com/viewtopic.php?f=10&t=29377&hilit=greece

Recommended literature for this series !

My small collection of the Prefecture Stamps issued in 1990

Enjoy the read!