Double bassists looking for a great comprehensive reference for the life and times of Serge Koussevitzky should visit his excellent Wikipedia page. The former music director of the Boston Symphony and double bass soloist left quite a footprint on both the double bass world and the classical music world in general. Check out his Wikipedia page here.
I was quite honored to be able to do a recital on his former bass back in June. There is some information about this instrument and how it wound up being given to Gary Karr in this Wikipedia entry as well.