Caldwell, C. K. "Gilbreath's Conjecture." http://primes.utm.edu/glossary/page.php?sort=GilbreathsConjecture.Debono, A. N. "Numbers and Computers (11): More on Primes." http://www.eng.um.edu.mt/~andebo/numbers/numcom11.htm.Gardner, M. "Patterns in Primes are a Clue to the Strong Law of Small Numbers." Sci. Amer.243, 18-28, Dec. 1980.Guy, R. K. "Gilbreath's Conjecture." §A10 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 25-26, 1994.Kilgrove, R. B. and Ralston, K. E. "On a Conjecture Concerning the Primes." Math. Tables Aids Comput.13, 121-122, 1959.Odlyzko, A. M. "Iterated Absolute Values of Differences of Consecutive Primes." Math. Comput.61, 373-380, 1993.Proth, F. "Sur la série des nombres premiers." Nouv. Corresp. Math4, 236-240, 1878.Sloane, N. J. A. Sequences A000232/M2718 and A036262 in "The On-Line Encyclopedia of Integer Sequences."