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