Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
ban hanh » ban hang
sach ty » sach y, sach tu, sach thu
ty tang » tay tang, ty xang, ty hang
tang co » tang cho, nang co, tang o
hieu va » lieu va, hieu qua
cac xuc » cam xuc, cac nuoc, chat xuc
cua cau » cua cac, cua chu, cua cay
di cua » dai cua, doi cua, de cua

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 tang co hoc. hieu va cac xuc ((van ban) or (ban hanh)) di cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ty tang co hoc. hieu va cac xuc ((van ban) OR (ban hanh)) di cua cau*.