Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cac tren » cau tren, rac tren, tac tren
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
lam duc » lam duoc, pham duc, nam duoc
van lam » van nam
tu cach » tu cac
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
te sach » toc sach
ca tren » cau tren, cu tren, la tren

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (te sach)) ky tang xa hoi. hieu van lam duc va hanh va ((cac tren) OR (ca tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (te sach)) ky tang xa hoi. hieu van lam duc va hanh va ((cac tren) OR (ca tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (te sach)) ky tang xa hoi. hieu van lam duc va hanh va ((cac tren) OR (ca tren))".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (te sach)) ky tang xa hoi. hieu van lam duc va hanh va ((cac tren) OR (ca tren))*.