Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va trien » va truyen, va thiet, va tuyen
nang xa » nang x, lang xa, nang ma
hieu va » hieu qua
xuc van » luc van, vuc van, xuc ban
duc van » duc va, duc tan, duc manh
hanh de » hanh ve, hanh kem
sach 2 » sach y
2 nang » v nang
de va » de van, te va, ke va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach 2 nang xa hoi. ((hieu va) or (lieu va)) cam ((xuc van) or (duc van)) hanh de va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach 2 nang xa hoi. ((hieu va) OR (lieu va)) cam ((xuc van) OR (duc van)) hanh de va trien.
• Adding a wildcard symbol may retrieve word variants: toc sach 2 nang xa hoi. ((hieu va) or (lieu va)) cam ((xuc van) or (duc van)) hanh de va trien*.