Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
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
dat sach » mat sach, dat khach, nam 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 sach)) - hanh trinh vat dang ((cong vang) OR (cong lang)) toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((hau sach) or (dat sach)) - hanh trinh vat dang ((cong vang) OR (cong lang)) toan cau~".
• Adding a wildcard symbol may retrieve word variants: theo ((hau sach) or (dat sach)) - hanh trinh vat dang ((cong vang) OR (cong lang)) toan cau*.