Literature G-Class

Hello together, have read with much pleasure the book of Mr. Jörg Sand „Das Neue Grosse Mercedes G-Class-Buch (2011). I thought, I ask you for your current book recommendations, especially on the topic of self-help/screws at the G. The internet pages of Dr. Hans Hehl are legend. Where can you find more, and the matching MB original manual to the G? Thank you for your help. becasse