We answer two questions on Pell's equations and periods of quadratic irrationals raised by the second author while computing some cohomology groups.
Qiang Lin. Takashi Ono. "On two questions of Ono." Proc. Japan Acad. Ser. A Math. Sci. 78 (10) 181 - 184, Dec. 2002. https://doi.org/10.3792/pjaa.78.181