Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
xang cao » nang cao, lang cao, quang cao
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
cao hoc » co hoc, cho hoc, chat hoc
anh vi » hanh vi, anh va, anh vu
anh ve » hanh ve, anh va, anh viet
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 xang cao hoc. hieu ve cac vuc van ((anh vi) or (anh ve)) cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty xang cao hoc. hieu ve cac vuc van ((anh vi) OR (anh ve)) cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty xang cao hoc. hieu ve cac vuc van ((anh vi) or (anh ve)) cua cau*".