>>705
>Katz & Katz (2010b)は、ご夫婦の数学者かな?

これか
https://arxiv.org/abs/1007.3018
When is .999... less than 1?
Karin Usadi Katz, Mikhail G. Katz
Journal reference: Montana Mathematics Enthusiast 7 (2010), 3--30
https://arxiv.org/pdf/1007.3018.pdf