... 24 (1995), 126 1- 127 9. [ 24 ] Nguyễn Thành Long, Trần Minh Thuyết, On the existence, uniqueness of solution of the nonlinear vibrations equation , Demonstratio Math. 32 (1999), 749 - 758. [25 ] ... ),( 2 ),,,,( tx uuutxf associated with the mixed homogeneous conditions , J. Math. Anal. Appl. 2 74, No.1 (20 02) , 1 02- 123 . [28 ] Nguyễn Thành Long, On the nonlinear wave equation ,,( 2 utBu ... wave equation ,(tBu tt − ),,,,,() 22 xtxxxx uuuutxfuu = associated with the mixed nonhomogeneous conditions , J. Math. Anal. Appl. 29 2 (20 04) , No .2, 43 3 -45 8. [31] Nguyễn Thành Long, Bùi Tiến...