any chance you read German? Or Finnish?
Best book is probably Drei Linine Gewehr by Karl-Heinz Wrobel. 2 Volume set. Hard to find though and expensive (and written in German).
Sadly, the best references on many arms are not in English
Looks like you already have the two best English references, though they are both out of date.
Also check out www.Mosinnagant.net and www.7.62x54R.net