Perhaps you should try some spelling variations:
cau triet » cau trieu, su triet, cua triet
hang doi » hang di, hang loi, huong doi
toc sach » hoc sach, doc sach, thuoc sach
hieu va » lieu va, hieu qua
sach tu » sach thu, cach tu, sach ty
va hang » van hang, va nang, va lang
tu nang » tru nang, tu nong, tu nano
cua tre » cua te, cuu tre, cua triet
cam tu » cam thu, nam tu, dam tu
va cam » va cham, va cac, va cao
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach tu nang ((x hoi) OR (o hoi)). hieu va cam tu va hang doi ((cua tre) or (cau triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tu nang ((x hoi) OR (o hoi)). hieu va cam tu va hang doi ((cua tre) OR (cau triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tu nang ((x hoi) OR (o hoi)). hieu va cam tu va hang doi ((cua tre) or (cau triet))".
• Adding a wildcard symbol may retrieve word variants: toc sach tu nang ((x hoi) OR (o hoi)). hieu va cam tu va hang doi ((cua tre) or (cau triet))*.