Perhaps you should try some spelling variations:
chiet tach » chieu sach
thien hach » thien thanh
hien hanh » dieu hanh
hanh dung » thanh dung, anh dung, hanh dong
dong cong » duong cong, dung cong, dang cong
tai dong » thai dong, tai cong, tai tong
cong tan » cong tac, cong san, cong thanh
tan chan » dan chan, ban chan, can chan
chan cau » phan cau, can cau, chinh 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: hoc ((((thien hach) OR (hien hanh))) OR (chiet tach)) - hanh dung tai dong cong tan chan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((((thien hach) OR (hien hanh))) or (chiet tach)) - hanh dung tai dong cong tan chan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc ((((thien hach) OR (hien hanh))) or (chiet tach)) - hanh dung tai dong cong tan chan cau*.