Perhaps you should try some spelling variations:
trinh khien » trinh thien, trinh nghien, trinh thiet
hanh trinh » canh tranh, hanh chinh
khien bang » phien ban, khien dong
hien sach » dien sach, kien sach, thien hach
bang cong » dang cong, bang song, hang cong
cong van » cong vang, cong san, song van
bang cac » hang ca, dung cac, hang cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hien sach - hanh trinh khien bang cong van ((bang cac) or (nang cao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hien sach - hanh trinh khien bang cong van ((bang cac) OR (nang cao)).
• Adding a wildcard symbol may retrieve word variants: hoc hien sach - hanh trinh khien bang cong van ((bang cac) or (nang cao))*.