Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
dat khach » dat khanh, vay khach, can khach
trinh vat » trinh van, trinh luat, sinh vat
cong vang » cong quang, cong ngang, cong san
cong lang » cong luong, cong quang, cong ngang
hau sach » khau sach, cau sach, ham sach
vat dang » van dang, vat dung, va dang
toan cau » toan cao, toan ban, toan tap

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: theo ((hau sach) OR (dat khach)) - hanh trinh vat dang ((cong vang) OR (cong lang)) toan cau~.
• Adding a wildcard symbol may retrieve word variants: theo ((hau sach) or (dat khach)) - hanh trinh vat dang ((cong vang) or (cong lang)) toan cau*.