Have just received a wonderful book by Andreas Thoma “Vertrackte Retraktoren”! Though retractors are not my main interest, so nicely made 160 pages of the book, including 531 problem, articles and comics (by Claus Grupen) invite to have a closer look!
You’re welcome to buy it from Andreas, just contact him by e-mail: firstname.lastname@example.org.
Vertrackte Retraktoren = Dirty retractors(?)
I would say “Complicated Retractors”, but the tricky & clever German alliteration would be gone. An excellent book, by the way!
Or you could translate “vertrackte” as “tricky” – just like the alliteration in the title!
But have no fear, actually most of the retractors are short and with only a few pieces on the board, not very tricky at all, and they should be understandable to anyone.