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