The Bernina Overlockboek is a very interesting source of information about the overlocker. It is written in the Dutch language, therefore unfortunately only interesting for our Dutch readers.
Nevertheless we want to inform you about this book because it is a great book with a lot of information, instructions and inspiration.
Bernina offers e-books about the sewingmachines and the sergers as well on this link:
Good luck with the books. The Bernina Overlockboek is worth every eurocent....