Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va trien » va truyen, va thiet, va tuyen
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
qua cam » qua cham, qua cac, qua ca
xuc van » duc van, vuc van, xuc ban
luc van » luoc van, luu van, duc van
hanh ve » hanh vi, hanh va, hanh kem
ve va » ve 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: ((te sach) OR (toc sach)) ky lang xa hoi. hieu qua cam ((xuc van) or (luc van)) hanh ve va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky lang xa hoi. hieu qua cam ((xuc van) OR (luc van)) hanh ve va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky lang xa hoi. hieu qua cam ((xuc van) or (luc van)) hanh ve va trien".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky lang xa hoi. hieu qua cam ((xuc van) or (luc van)) hanh ve va trien*.