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
bang cong » bang song, hang cong, dung cong
dang cong » dung cong
van hang » van khang, van hoang, van thang
hang ca » hang va, nang cao, hang tai

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