Squares with No More than 2 Distinct Digits/Historical Note

Historical Note on Squares with No More than 2 Distinct Digits
Writing in $1997$, reports in his  attributes the largest known square numbers which has no more than $2$ distinct (non-zero) digits, $6\,661\,661\,161$, to Yoshigahara.

It is assumed that this is the renowned puzzler.