This chapter is based in part on
Abramowitz and Stegun (1964, Chapter 7) by Walter Gautschi. Walter Gautschi
provided the author with a list of references and comments collected since
the original publication.
For general bibliographic reading see Carslaw and Jaeger (1959),
Lebedev (1965), Olver (1997b), and Temme (1996b).