Perhaps you should try some spelling variations:
vien nganh » vien thanh
hanh trinh » canh tranh, hanh chinh
thuong ban » thuong han, thuong lan, tuong ban
hieu xanh » chieu xanh, hieu manh, hieu nganh
khoan cam » khoa cam, khoan va, phan cam
trinh ha » trinh han, trinh hoa, trinh nha
khan cap » khan ap, than cap, phan cac
ha hang » nha hang, ha tang, va hang

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu xanh) or (vien nganh)) - hanh trinh ha hang thuong ban ((khan cap) OR (khoan cam))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu xanh) OR (vien nganh)) - hanh trinh ha hang thuong ban ((khan cap) OR (khoan cam)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu xanh) or (vien nganh)) - hanh trinh ha hang thuong ban ((khan cap) OR (khoan cam))".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu xanh) or (vien nganh)) - hanh trinh ha hang thuong ban ((khan cap) OR (khoan cam))*.