Perhaps you should try some spelling variations:
trinh thiet » trinh viet, trinh thi
hanh trinh » canh tranh, hanh chinh
hien sach » dien sach, kien sach, thien hach
dang cong » dung cong
bang song » nang song
van bang » van ban, van nang, von bang
bang cac » nang cao, hang ca, dung cac

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 thiet ((dang cong) or (bang song)) van bang cac~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hien sach - hanh trinh thiet ((dang cong) OR (bang song)) van bang cac.
• Adding a wildcard symbol may retrieve word variants: hoc hien sach - hanh trinh thiet ((dang cong) or (bang song)) van bang cac*.