Perhaps you should try some spelling variations:
trinh khong » tinh khong, trinh khung, thinh khong
hanh trinh » canh tranh, hanh chinh
sach tranh » canh tranh
tranh cong » thanh cong, trinh cong, tran cong
khong khi » khong he
cong hai » cong thai, cong ha, hoang hai
du hanh » dieu hanh, duy khanh, luu hanh
vu sach » vu bach, su sach, vu khach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( du hanh trinh khong khi đong luc ) or ( vu sach tranh cong hai đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( du hanh trinh khong khi đong luc ) OR ( vu sach tranh cong hai đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( du hanh trinh khong khi đong luc ) or ( vu sach tranh cong hai đong luc ))*.