Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc van » thuc vat, thuc dan, thuc hanh
sach ty » sach y, sach tu, sach thu
thuc va » thuc vat, thuc dan, thuc day
cua cau » cua cac, cua chu, cua cay
hieu ve » hieu va, hieu van
cho hoc » khoa hoc
ty nang » ky nang, ty xang, ty hang
anh vi » hanh vi, anh va, anh ve
vi cua » vai cua, di cua
ve cac » va cac, vien cac

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: toc sach ty nang ((cho hoc) OR (co hoc)). hieu ve cac ((thuc van) OR (thuc va)) anh vi cua cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang ((cho hoc) or (co hoc)). hieu ve cac ((thuc van) OR (thuc va)) anh vi cua cau~".
• Adding a wildcard symbol may retrieve word variants: toc sach ty nang ((cho hoc) or (co hoc)). hieu ve cac ((thuc van) OR (thuc va)) anh vi cua cau*.