Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
minh vi » minh voi, dinh vi, minh va
vuc van » duc van, luc van, thuc van
cac vuc » cac nuoc, cac vung, cac cuoc
hieu ve » hieu va, hieu van
cua cau » cua cac, cua chu, cua cay
cho hoc » khoa hoc
tu ngan » vu ngan, tu ngay, te ngan
ve cac » va cac, vien cac
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) tu ngan ((cho hoc) OR (co hoc)). hieu ve cac vuc van minh vi cua cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) tu ngan ((cho hoc) or (co hoc)). hieu ve cac vuc van minh vi cua cau~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) tu ngan ((cho hoc) or (co hoc)). hieu ve cac vuc van minh vi cua cau*.