Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va nang » van nang, da nang, cam nang
nang di » nang du, hang di, nang ji
cua tre » cua te, cuu tre, cua triet
nam tu » nam thu, nam thuc
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang x ho. ((hieu quan) or (hieu qua)) nam tu va nang di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x ho. ((hieu quan) OR (hieu qua)) nam tu va nang di cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x ho. ((hieu quan) or (hieu qua)) nam tu va nang di cua tre*.