Very interesting 119

I find this very interesting book.
As there is very little text, does it in English is not a problem for those who have difficulty with the language.
One caveat: what bothered me as a beginner is that the bosses nothing indicates that we must cut or leave. A simple cross would suffice as an indication.
I solved this problem by scanning the pattern in a drawing program and filling with color the part to be left. It is quick to perform.