Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hai truc » dai truc, hai trac, hang truc
cua tre » cuu tre, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
van hai » van ha, van chat, van hanh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua te » cua tu

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

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