Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
danh gia » dan gian
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
van cac » van hac, van cau, van bac
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
su tien » su kien, su hien, tu tieng
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
gia su » gia suc, giao su, gia sa

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 ty ((nang xa) or (lang xa)) hoi. hieu van cac ((xuc va) OR (tuc va)) danh gia su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ty ((nang xa) OR (lang xa)) hoi. hieu van cac ((xuc va) OR (tuc va)) danh gia su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ty ((nang xa) or (lang xa)) hoi. hieu van cac ((xuc va) OR (tuc va)) danh gia su tien".
• Adding a wildcard symbol may retrieve word variants: doc sach ty ((nang xa) or (lang xa)) hoi. hieu van cac ((xuc va) OR (tuc va)) danh gia su tien*.