1. Combinatorial Identities;Gould,1972
2. Research Bibliography of Two Special Number Sequences;Gould,1976
3. Über Unterbäume eines Baumes;Izbicki;Monatsh. Math.,1970
4. A note on Catalan parentheses;Riordan;Amer. Math. Monthly,1973
5. Catalan numbers and “total information” numbers;Shapiro,1975