Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
duc cuu » duc suu
va minh » van minh, vua minh, va kinh
cao suc » cao su, cao duc
cao luc » bao luc, cao duc, cau luc
cuu tre » cua tre, cau tren, cau treo
hieu va » lieu va, hieu qua
ty nang » ky nang, ty hang, ly nang

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