2 citations to https://www.mathnet.ru/rus/im958

1. Getmanenko A., “Shatalov-Sternin's construction of complex WKB solutions and the choice of integration paths”, Math. Nachr., 287:14-15 (2014), 1642–1658            
2. Boris Sternin, Victor Shatalov, “On a Nation of Resurgent Function of Several Variables”, Math Nachr, 171:1 (1995), 283