Perhaps you should try some spelling variations:
trinh chuan » trinh han, trinh quan, trinh luan
thuat sach » thuat lanh, thuat san
canh trinh » canh tranh, hanh trinh, canh tinh
hoc thuat » hoc thuyet, hoc thuc, hoc chat
dung cong » dung trong
thang van » tang van, thanh van, thong van
van cau » van dau, van hau, van chat

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc thuat sach - canh trinh chuan ((dung cong) or (dang cong)) thang van cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thuat sach - canh trinh chuan ((dung cong) OR (dang cong)) thang van cau*.