Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
vu khach » vu khanh, vu khac, vay khach
nam thuc » nam thuoc, am thuc, nam thu
khach ky » hanh ky, thanh ky
hieu van » hieu va, thien van, lieu va
cua viet » ca viet, hoa viet, cua vat
lang van » dang van, tang van, hoang van
va hanh » van hanh, va thanh, va danh
lang xa » lang ha, dang xay
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu khach ky ((lang xa) or (lang van)) hoi. hieu van nam thuc ((va hanh) or (ban thanh)) vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu khach ky ((lang xa) OR (lang van)) hoi. hieu van nam thuc ((va hanh) OR (ban thanh)) vi cua viet.
• Adding a wildcard symbol may retrieve word variants: vu khach ky ((lang xa) or (lang van)) hoi. hieu van nam thuc ((va hanh) or (ban thanh)) vi cua viet*.