Perhaps you should try some spelling variations:
thieu sach » chieu sach, hieu cach, theo sach
thien hach » thien thanh, hien hanh
thanh tung » thanh cong
ung song » vung song, xuong song, nang song
song tan » song than, song van, cong tan
van chat » cao chat
tan van » tran van, tang van, luan van

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu sach) or (thien hach)) - ((thanh trung) or (thanh tung)) dap ung song tan van chat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (thien hach)) - ((thanh trung) OR (thanh tung)) dap ung song tan van chat.
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sach) or (thien hach)) - ((thanh trung) or (thanh tung)) dap ung song tan van chat*.