Perhaps you should try some spelling variations:
doan truc » doan trung, xuan truc, doan tu
dau truc » cau truc, dai truc, dau tu
hanh vai » hanh vi, hanh va, hanh tai
dang xay » dang van, van xay
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
sac ky » cac ky, sai ky
tu sac » tu sach, tu cac, tu san

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 ky ((nang cao) OR (dang xay)) hoi. hieu va ((dau truc) OR (doan truc)) va hanh vai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky ((nang cao) or (dang xay)) hoi. hieu va ((dau truc) OR (doan truc)) va hanh vai cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu sac ky ((nang cao) or (dang xay)) hoi. hieu va ((dau truc) OR (doan truc)) va hanh vai cua tre*.