1. Functional equations connected with the Collatz problem;Berg;Results Math.,1994
2. The 3n+1 Collatz problem and functional equations;Berg;Rostock. Math. Kolloq.,1995
3. Functions of One Complex Variable;Conway,1973
4. Studies on Divergent Series and Summability and The Asymptotic Developments of Functions Defined by Maclaurin Series;Ford,1960
5. Stochastic models for the 3x+1 and 5x+1 problems and related problems;Kontorovich,2010