Avalanche book information needed

Hi (expert) reader(s)

I want to know more about the fundamentals of avalanches,
like stability, the underground influence, the composition of the snowpack
etc.
Well the usual stuff a backcountry boarder need to know and should know.

Does anybody know a good (extensive) book about avalanches?

Keep on riding,
Andre

Note: I fully understand that it is not a replacement for a course but i
want to be prepared
before following a course.