References

E. Belaga, "Reflecting on the 3x+1 Mystery. Outline of a scenario - improbable or realistic?", 1998, preprint. Available at http://citeseer.nj.nec.com/belaga98reflecting.html

M. Chamberland, "A continuous extension of the 3x+1 problems to the real line", Dynam. Contin. Discrete Impuls. Systems 2:4 (1996), 495–509.

J. C. Lagarias, "The 3x+1 problem and its generalizations", Amer. Math. Monthly 92:1 (1985), 3–23.

S. Letherman, D. Schleicher, and R. Wood, "The 3n+1 problem and holomorphic dynamics", Experimental Mathematics 8 (1999) 241–251.