“…are fulfilled. To these w1 (x) and w2 (x), via formulae (31) and (32) there correspond another pair of functions p(x) and q(x) such that (p, q) = (p, q). Then, analogously to the above, relations (28), (35) and (36) will mean that {λ n k,1 ,1 } k∈Z and {λ n k,2 ,2 } k∈Z are subspectra also of the problems B 1,1 ( Q) and B 1,2 ( Q), respectively, with Q = Q.…”