Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang xay » dang van, van xay
danh gia » dan gian
hieu van » hieu va, thien van, lieu va
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, sach thu
cac luc » cau luc, cac nuoc, cac cuoc
va danh » va dinh, va dan, va hanh
su tien » su kien, su hien, tu tieng
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: toc sach ty ((nang xa) or (dang xay)) hoi. hieu van ((cac luc) OR (coc luc)) va danh gia su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((nang xa) OR (dang xay)) hoi. hieu van ((cac luc) OR (coc luc)) va danh gia su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty ((nang xa) or (dang xay)) hoi. hieu van ((cac luc) OR (coc luc)) va danh gia su tien".
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((nang xa) or (dang xay)) hoi. hieu van ((cac luc) OR (coc luc)) va danh gia su tien*.