Perhaps you should try some spelling variations:
hieu sach » chieu sach, hieu cach, dien sach
tran tuan » tran xuan, tran thanh, tranh luan
tong cong » trong cong, cong cong, dung cong
doc hieu » toc thieu, hoc thieu, hoc hien
cong tan » cong tac, cong san, cong thanh
tan can » toan can, tan van, ban can
can cau » van cau, ban cau, ca cau

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sach - hanh ((tran tuan) OR (tran quang)) tong cong tan can cau~.
• Adding a wildcard symbol may retrieve word variants: doc hieu sach - hanh ((tran tuan) or (tran quang)) tong cong tan can cau*.