Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
chat cuu » chat huu, chat cua, cham cuu
van hanh » van thanh, ban hanh, van anh
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
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: tu sac ky ((nang xa) or (lang xa)) hoi. ((hieu van) OR (hieu va)) chat cuu van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky ((nang xa) OR (lang xa)) hoi. ((hieu van) OR (hieu va)) chat cuu van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky ((nang xa) or (lang xa)) hoi. ((hieu van) OR (hieu va)) chat cuu van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ky ((nang xa) or (lang xa)) hoi. ((hieu van) OR (hieu va)) chat cuu van hanh vi cua tre*.