Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau treo » cau theo, cau triet, cau trieu
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
loc va » hoc va, luc va

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