Perhaps you should try some spelling variations:
nang giao » nang cao
hieu nang » lieu nang, hieu lang, sieu nang
duc toan » duc tan, duc ton, duc thang
duc hoan » duc hoang, duc hoa, duc thuan
thanh va » thanh van, hanh va, thanh ha
sach ky » sach y, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
va cua » va chua, via cua, ca cua
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 toan) OR (duc hoan)) thanh va cua tre~.
• 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 toan) OR (duc hoan)) thanh va cua tre.
• 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 toan) OR (duc hoan)) thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) or (sac ky)) nang x hoi. hieu nang giao ((duc toan) OR (duc hoan)) thanh va cua tre*.