Perhaps you should try some spelling variations:
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
vu sac » vu sach, vu san, va sac
sac ky » cac ky, sai ky
ma hoi » mai hoi, ma hoa, me hoi
ve hoc » te hoc, va hoc, vi hoc
vi cua » vai cua
di cua » dai cua, doi cua, de cua
nuoc » quoc, duoc, ngoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sac ky nang ((ma hoi) OR (xa hoi)). hieu ve hoc nuoc va hanh ((vi cua) or (di cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sac ky nang ((ma hoi) OR (xa hoi)). hieu ve hoc nuoc va hanh ((vi cua) OR (di cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sac ky nang ((ma hoi) OR (xa hoi)). hieu ve hoc nuoc va hanh ((vi cua) or (di cua)) tre".
• Adding a wildcard symbol may retrieve word variants: vu sac ky nang ((ma hoi) OR (xa hoi)). hieu ve hoc nuoc va hanh ((vi cua) or (di cua)) tre*.