[1] Cai Tianxin, The Book of Numbers, Higher Education Press, 2015,
46-47.
[2] J. C. Lagarias, The 3x + 1 problem and its generalizations,
The American Mathematical Monthly 92(1) (1985), 3-23.
DOI: https://doi.org/10.2307/2322189
[3] E. Heppner, Eine Bemerkung zum hasse-syracuse-algorithmus, Archiv
der Mathematik 31(1) (1978), 317-320.
DOI: https://doi.org/10.1007/BF01226454
[4] Keith R. Matthews, The ultimate challenge: The 3x + 1
problems, American Mathematical Society (2010), 79-103.
[5] J. C. Lagarias, The 3x + 1 Problem: An Annotated
Bibliography, II (2000-2009), arXiv:math/0608208v6.
[6] Marc Chamberland, Averaging structure in the 3x + 1
problem, Journal of Number Theory 148 (2015), 384-397.
DOI: https://doi.org/10.1016/j.jnt.2014.09.024
[7] Aristides V. Doumas and Vassilis G. Papanicolaou, A randomized
version of the Collatz 3x + 1 problem, Statistics & Probability
Letters 109 (2016), 39-44.
DOI: https://doi.org/10.1016/j.spl.2015.10.017
[8] Dora M. Ballesteros, Jimmy Pena and Diego Renza, A novel image
encryption scheme based on Collatz conjecture, Entropy 20(12) (2018);
Article 901.
DOI: https://doi.org/10.3390/e20120901