Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
ban truc » ba truc, ban thuoc, xuan truc
dua tren » dung tren
cau treo » cau theo, cau tren, cau triet
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
truc va » thuc va, thuc vat, trung va
y nang » ky nang, ly nang, v nang
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 (lieu va)) ban truc va dan vi ((dua tren) or (cau treo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang xa hoi. ((hieu van) OR (lieu va)) ban truc va dan vi ((dua tren) OR (cau treo)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang xa hoi. ((hieu van) OR (lieu va)) ban truc va dan vi ((dua tren) or (cau treo))".
• Adding a wildcard symbol may retrieve word variants: su sach y nang xa hoi. ((hieu van) OR (lieu va)) ban truc va dan vi ((dua tren) or (cau treo))*.