Perhaps you should try some spelling variations:
nang giao » nang cao
hieu nang » lieu nang, hieu lang, sieu nang
tan thanh » tran thanh, tang thanh, toan thanh
cua triet » cua viet, su triet, va triet
thanh va » thanh van, hanh va, thanh ha
sach ky » sach y, sach ty, sach kem
cua tre » cua te, cuu tre, dua tren
sac ky » cac ky, sai ky
x hoi » xa hoi, o hoi, x ho

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 ky) or (sac ky)) nang x hoi. hieu nang giao duc tan thanh va ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sac ky)) nang x hoi. hieu nang giao duc tan thanh va ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) or (sac ky)) nang x hoi. hieu nang giao duc tan thanh va ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) or (sac ky)) nang x hoi. hieu nang giao duc tan thanh va ((cua tre) OR (cua triet))*.