Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang xay » dang van, van xay
ky dang » ky nang, ky danh
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » lieu va, hieu qua
hai cua » thai cua, dai cua, hoi cua
sach ky » sac ky, sach y, sach ty
lai cua » dai cua, lai chau, thai cua
loc va » hoc va, luc va
tuc va » thuc va, truc va, tuc xa
va cau » van cau, va cac, va dau

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 dang xay hoi. hieu va cau ((loc va) or (tuc va)) danh ((lai cua) OR (hai cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang xay hoi. hieu va cau ((loc va) OR (tuc va)) danh ((lai cua) OR (hai cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky dang xay hoi. hieu va cau ((loc va) or (tuc va)) danh ((lai cua) OR (hai cua)) te".
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang xay hoi. hieu va cau ((loc va) or (tuc va)) danh ((lai cua) OR (hai cua)) te*.