There is some excellent information in this document - which JonHack1 has described in some detail.
However, I feel I must mention that it is VERY hard work to read.
This may partly be due to translation problems.
EG. "Either......either......" is presumably a literal translation from German; whereas in English we say "either.......or.......". Things like this mean the reader needs to unpick sentences to make sense of them.

But largely, it seems to me, the problems are due to the structure of the document (so presumably would also be pretty confusing in German too).
EG. After a VERY brief intro to the concept of clocking, the author plunges into a discussion of the problems of casting out 13's. This is without any explanation of what casting out is (which I already knew, but others might not). And - more importantly I think - without any explanation of why 13's might even be under discussion in the first place. In fact (I believe) this is the system recommended by Mike Powers - but it would be normal to introduce it first, and explain its claimed benefits. In fact it would be more normal to start with an overview of other systems (based on casting 10's) in order to build up to 13's. It's just really weird to start the document with why NOT to cast 13's!
This is just one example. The whole document is extremely terse, and assumes a LOT of knowledge/context that is not laid out easily for the reader.

However, the content itself is gold dust!

My favourite bits (so far) are -
1. The idea of casting 20's, rather than 10's or 13's

2. Solke's revised version of the Mingau system (section 3.1). This shows great mathematical insight. When I read it, I immediately thought "Yes, of course!"

3. Wasshuber’s Suit Addendum (section 3.4). This is an incredibly simple technique to determine whether there are an even or odd number of cards of a particular colour or suit in the deck. Another one of those things that made me say "Doh! Why didn't I think of that?"