The publication was obscure, and it is unclear if his proof directly involved 0.999..., but at least one modern proof by W. G. Leavitt does.
当初出版时没有写得很清楚，我们也不知道他的证明是不是直接提到了0.999…，但至少有一个W·G·莱维特的现代证明是这样的。