1. The Bender–Wu analysis and the Voros theory;Aoki,1991
2. The Bender–Wu analysis and the Voros theory. II;Aoki,2009
3. Resurgent methods in semi-classical asymptotics;Delabaere;Ann. Inst. Henri Poincaré,1999
4. Higher Transcendental Functions, I, II, III;Erdélyi,1955
5. On the WKB theoretic structure of the Schrödinger operators with a merging pair of a simple pole and a simple turning point;Kamimoto;Kyoto J. Math.,2010