Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
cam luc » cam xuc, cau luc
duc cuu » duc suu
va kinh » va tinh, qua kinh
va minh » van minh, vua minh, va tinh
cuu tre » cua tre, cau tren, cau treo
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
va cam » va cham, va cac, va cao

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)) ty nang xa hoi. hieu va cam luc ((va minh) OR (va kinh)) duc cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ty nang xa hoi. hieu va cam luc ((va minh) OR (va kinh)) duc cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) ty nang xa hoi. hieu va cam luc ((va minh) OR (va kinh)) duc cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ty nang xa hoi. hieu va cam luc ((va minh) OR (va kinh)) duc cuu tre*.