Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
lang xa » lang ha, dang xay, lang van
van cac » van hac, van cau, van bac
cac lop » cac hop, cac loai
va hanh » van hanh, va thanh, va danh
cua tre » cuu tre, cua triet, dua tren
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
lop va » lap va, hop va, nop va
cua te » cua tu

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: te sac ky ((nang x) OR (lang xa)) hoi. hieu van cac lop va hanh vi ((cua tre) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky ((nang x) or (lang xa)) hoi. hieu van cac lop va hanh vi ((cua tre) OR (cua te))~".
• Adding a wildcard symbol may retrieve word variants: te sac ky ((nang x) or (lang xa)) hoi. hieu van cac lop va hanh vi ((cua tre) OR (cua te))*.