Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
y nang » ky nang, ly nang, v nang
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va

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 y nang xa hoi. ((hieu van) OR (hieu va)) cac tuc va dan vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang xa hoi. ((hieu van) OR (hieu va)) cac tuc va dan vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang xa hoi. ((hieu van) OR (hieu va)) cac tuc va dan vi ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach y nang xa hoi. ((hieu van) OR (hieu va)) cac tuc va dan vi ((cua tre) or (cuu tre))*.