Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
qua cham » qua hai, qua cac, va cham
cham duc » pham duc, cham soc, pham duy
cau treo » cau theo, cau tren, cau triet
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
va dan » ca dan, va dao, va dau
dan di » danh di, dan da, dan de

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