. "See also 47H14, 58J37, 70H09, 81Q15." . . . . . . . . . . "\u6444\u52A8\u7406\u8BBA"@zh . . "Perturbation theory [See also 47H14, 58J37, 70H09, 81Q15]"@en . "47A55"^^ . "\u6444\u52A8\u7406\u8BBA[\u53C2\u89C147H14, 58J37, 70H09, 81Q15]"@zh . . . . . . "Perturbation theory "@en . .