1. Bruijn, N. G. De and P. Erdös. On a recursion formula and on some Tauberian theorems. Submitted to J. Research Nat. Bur. Standards.
2. A class of recurrence formulae;Cooper;J. London Math. Soc.,1947
3. A property of power series with positive coefficients;Erdös;Bull. Am. Math. Soc.,1949
4. On a sequence defined by a non-linear recurrence formula;Wright;J. London Math. Soc.,1945