Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tang cho » trang cho, sang cho, hang cho
hanh vu » hanh vi, hanh va, hanh tu
vuc van » duc van, luc van, thuc van
cac vuc » cac nuoc, cac vung, cac cuoc
cua cau » cua cac, cua chu, cua cay
hieu ve » hieu va, hieu van
cho hoc » co hoc, khoa hoc
ty tang » tay tang, ty xang, ty hang
anh vu » anh tu, anh va, anh ve
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ty tang cho hoc. hieu ve cac vuc van ((anh vu) or (hanh vu)) cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty tang cho hoc. hieu ve cac vuc van ((anh vu) OR (hanh vu)) cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty tang cho hoc. hieu ve cac vuc van ((anh vu) or (hanh vu)) cua cau*".