Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach ky » sac ky, sach y, sach ty
lai cua » dai cua, hai cua, thai cua
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
va cau » van cau, va cac, va dau
tuc va » thuc va, truc va, tuc xa
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 lang xa hoi. hieu va cau ((loc va) or (tuc va)) danh ((lai cua) OR (lai chau)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky lang xa hoi. hieu va cau ((loc va) OR (tuc va)) danh ((lai cua) OR (lai chau)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky lang xa hoi. hieu va cau ((loc va) or (tuc va)) danh ((lai cua) OR (lai chau)) te".
• Adding a wildcard symbol may retrieve word variants: toc sach ky lang xa hoi. hieu va cau ((loc va) or (tuc va)) danh ((lai cua) OR (lai chau)) te*.