“…If the above quantities are zero, then the corresponding zetafunctions are entire. The approximation of analytic functions by the functions ζ(s; a) and ζ(s, α; b) was studied in [8,26,28,29] and [2,7,18,22,24,25,27], respectively. The first joint results for a pair of functions ζ(s; a), ζ(s, α; b) has been obtained in [9].…”