“…For instance, the study of the size of the fundamental solution is an interesting problem addressed in several papers, e.g., [7,11,22]. Recently, the solvability of simultaneous Pell equations and explicit formulas for their solutions have been also studied in [14,8,12]. Moreover, it is also interesting to study the Pell equation over finite fields, determining the number of solutions and their properties [18,20,19,9].…”