Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
dinh ke » dinh ket, dinh ve, dinh le
thuc va » thuc vat, thuc dan, thuc day
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
van cam » van nam, van lam, van cau
xuc va » duc va, tuc va, luc va
ke va » te va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ky tang xa hoi. hieu van cam ((xuc va) or (thuc va)) dinh ke va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky tang xa hoi. hieu van cam ((xuc va) OR (thuc va)) dinh ke va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky tang xa hoi. hieu van cam ((xuc va) or (thuc va)) dinh ke va trien".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky tang xa hoi. hieu van cam ((xuc va) or (thuc va)) dinh ke va trien*.