Perhaps you should try some spelling variations:
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, va danh
sac ky » cac ky, sai ky
va xay » va xac
vi cua » vai cua
di cua » dai cua, doi cua, de cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sac ly) OR (sac ky)) va xay hoi. hieu va cac duc va hanh ((vi cua) OR (di cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sac ly) OR (sac ky)) va xay hoi. hieu va cac duc va hanh ((vi cua) or (di cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: tu ((sac ly) OR (sac ky)) va xay hoi. hieu va cac duc va hanh ((vi cua) or (di cua)) tre*.