Excerpt - page 7: " ... data structures is that they are always persistent -updating a functional data structure does not destroy the existing version"
3.
Data Structure Through C
by Yashavant Kanetkar and Abduln A.P.J. Kalam
(Paperback - 28 Feb 2003)
Excerpt - page 163: " ... memory and thus will invalidate element handles stored outside the data structure. There are many more tricks for implementing (external-memory) (a, b)- trees. We ... "