Bibliography

1

B.L. Schwartz, Finite Bounds on Digital Invariants - Some Conjectures, Journal of Recreational Mathematics, 3:2, pp. 88-92, April 1970

2

B. L. Schwartz, Finiteness of a Set of Self-Generating Integers, J. Recreational Mathematics, 2:2, pp. 79-83, 1969.

3

B. M. Stewart, Sums of Functions of Digits, Canad. J. Math. 12 (1960), 374-389.

4

Dik Winter's Website, http://www.cwi.nl/ dik/english/mathematics/armstrong.html This site contains a list of all PPDIs in bases 2-16

5

The GNU Multiprecision Library Homepage, http://swox.com/gmp/

6

Lionel T. Deimel, Jr., Michael T. Jones, Finding PluPerfect Digital Invariants: Techniques, Results and Observations, J. Recreational Mathematics, 14:2, pp. 87-107, (1981-1982).

7

Lionel T. Deimel, Jr.'s Website, http://www.deimel.org/rec_math/rec_math.htm

8

Problem E 1651, Amer. Math. Monthly, 71 (1964) 781.

9

Pudokkottai K. Subramanian, On Bases and Cycles, Mathematics Magazine, 41 (1968) 117-123.

10

Solution to Problem E 1651, Amer. Math. Monthly, 71 (1964) 1041.

11

Walter Schneider's Website,
http://www.wschnei.de/digit-related-numbers/pdi.html
This site contains descriptions of PDIs, PPDIs, and many other types of Narcissistic Numbers; has a table of base 10 PDIs up to order 100