Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cac thuc » cach thuc, cac thu, can thuc
nang xa » nang x, lang xa, nang ma
van cac » van hac, van cau, van bac
sach ty » sach y, sach tu, sach thu
thuc va » thuc vat, thuc dan, thuc day
va dinh » van dinh, va kinh, va tinh
dinh di » dinh du, dinh vi, danh di
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo

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

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