Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thu nang » thi nang, thu hang, thu bang
thuc dan » thuc hanh, hoc dan, thuc vat
minh vi » minh voi, dinh vi, minh va
duc van » duc va, duc tan, duc manh
hieu ve » hieu va, hieu van
cua cau » cua cac, cua chu, cua cay
nang co » nang cao, nang doc, nang noi
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)) thu nang co hoc. hieu ve cac ((thuc dan) OR (duc van)) minh vi cua cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) thu nang co hoc. hieu ve cac ((thuc dan) or (duc van)) minh vi cua cau~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) thu nang co hoc. hieu ve cac ((thuc dan) or (duc van)) minh vi cua cau*.