Is There Any Specialized Catalog For Notopfer Stamps Only?

I think that PostmasterGS will know the answer on this question?

A lot of pages are dedicated to that issue in Michel Specialized 2, but I can still see (on the market) a lot of different varieties which are not catalogized in the Michel 2. For example, it looks that a lot of private perforated Notopfers appeard... and a lot of the with some kind of errors.

Is there any handbook or catalogue which could be used as a final reference book for the notopfer issues?

How is your German? Peter Harlos specialized handbook.http://philabooks.com/pages/Liste.a...=1320&SORT=6 http://www.catawiki.com/catalog/sta...948-notopfer

The "Blue Flea"http://www.germanyphilatelicsociety...lea/flea.pdf

Hi! Thank you!

I am suppose that a set of 2 books by Schröder & co are more extensive than one single by Harlos? The entire 2nd volume (260 pages) is dedicated to private and postmasters' perforations. I suppose that those 2 books are going to be the ulimate guide for ALL the notpofer varieties.