[1] Bitsadze A V. Differential Equations of Mixed Type. New York: Macmillan Co, 1964

[2] Chen Shuxing. Introduction to Modern Partial Differential Equaitons. Beijing: Science Press, 2005

[3] Chen Shuxing. Study on Mach reflection and Mach configuration. to appear

[4] Gilbarg D, Trudinger N S. Elliptic Partial Differential Equation of Second Order. Grundlehren der Math-
ematischen Wissenschaften, 224. 2nd ed. Berlin New York: Springer, 1983

[5] Hua Loo-keng. On Lavrentiev partial differential equation of the mixed type. Scientia Sinica, 1964, 13: 1755–1762

[6] Lavrentiev M A, Bitsadze A V. On problem of mixed type equations. Dokl Akad Nauk, SSSR, 1950, 70: 373–376

[7] Ma Zhongtai, Xu Guangshan. Oblique derivative boundary value problems of mixed type equation. Ann Diff Equs, 2006, 22: 40–47

[8] Pulikin S P. Tricomi problem for a generalized Lavrentiev-Bitsadze equation. Dokl Akad Nauk, SSSR, 1958, 118: 38–41

[9] Rassias J M. Lecture Notes on Mixed Type Partial Differential Equations. Singapore, New Jersey, London,
Hong Knog: World Scientific, 1990

[10] Smirnov M M. Equations of Mixed Type. Translations of Mathematical Monograph, 51. Providence RI: Amer Math Soc, 1978

[11] Tricomi F. Sulle equazioni lineari alle derivate parziali di secondo ordino, di tipo misto. Rendiconli, Alli dell’ Accademia Nazionalw dei Lincei, 1923, 14: 134–247

[12] Wen G. Oblique derivative problems for linear mixed type equations of second order. Sci in China Ser A,
1998, 41: 285–295