pcf theory, as developed in Shelah's book "Cardinal Arithmetic", was
developed not only to compute or estimate the values
of the gimel function kappa^(cf(kappa) [from which one can
then compute arbitrary powers kappa^lambda], but rather to
** analyse the order-theoretic
structure of products kappa^(cf(kappa))**
for singluar cardinals kappa, or more generally , of products of the form
product_i lambda_i , where (lambda_i: i < delta) is a short sequence
of regular cardinals.

The table of contents for the "Cardinal arithmetic" book, together with the introduction, is available as a DVI file.

Saharon Shelah has also written several other Books.