Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang xa » nang x, lang xa, nang ma
qua cac » cua cac
cac luc » cau luc, coc luc, cac nuoc
va chua » vua chua, ca chua, va chu
y nang » ky nang, ly nang, v nang
luc va » duc va, tuc va, loc va
va dan » ca dan, va dao, va dau
va cua » via cua, ca cua, ma cua

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)) y nang xa hoi. hieu qua cac luc va dan ((va cua) or (va chua)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y nang xa hoi. hieu qua cac luc va dan ((va cua) OR (va chua)) viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) y nang xa hoi. hieu qua cac luc va dan ((va cua) or (va chua)) viet".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) y nang xa hoi. hieu qua cac luc va dan ((va cua) or (va chua)) viet*.