[1] He Y¨uzhan, Xian Xiuzhi. Agebriod funtion and ordinary differentia equations. Beijing: Science Press,
1988(in Chinese)

[2] L¨u Yinian, Zhang Guanghou. On the Nevanlinna directions of meromorphic funtions. Science in China,
1983: A(3): 215-224(in Chinese)

[3] Sun Daochun. The existence theorem of the Nevanlinna direction. Chinese Annals of Mathematics, 1986,
7A(2): 212-221(in Chinese)

[4] L¨u Yinian, Sun Daochun. Nevanlinna direction and Julia direction. Chinese Annals of Mathematics, 1992,
13A(3): 289-295(in Chinese)

[5] Zhang Xuelian. The defeciency of meromorphic functions and Nevanlinna directions. Jounal of Beijing
Institute of Technology, 1999, 8(1): 14-18(in Chinese)

[6] Sun Daochun. The basic theorem of cover surface theorem. Chinese Science Bulletin, 1994, 14(2): 213-
225(in Chinese)

[7] Zhang Xuelian. A fundamental inequality for meromorphic functions in an angular domain and its application.
Acta Mathematica Sinica(New Series), 1994, 10(3): 308-314(in Chinese)

[8] L¨u Yinian. Julia directions of meromorphic functions and meromorphic algebriod functions. Acta Mathematica
Sinica, 1984, 27(3): 367-373(in Chinese)

[9] L¨u Yinian, Gu Yongxing. On the existence of Borel directions for algebriod fungtions. Chinese Science
Bulletin, 1983, 3(5): 264-266(in Chinese)