Perhaps you should try some spelling variations:
thieu nien » thien nhien
hanh thai » nhanh thai, hinh thai, hanh tai
hieu vien » hieu hien, hieu viec, hieu tieng
thai cua » than cua, tai cuc, tri cua
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cuu tre, cua triet
duc van » duc va, duc tan, duc manh
cao duc » dao duc, cao suc, giao duc
tu bac » tu ban, tu cac, tu bat
nang o » nang co, nang ho, nang ro
tu san » thu san, tu ban, tu can
o lai » o lao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu bac) or (tu san)) ky nang o lai. ((hieu vien) OR (thieu nien)) cao duc van hanh thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu bac) OR (tu san)) ky nang o lai. ((hieu vien) OR (thieu nien)) cao duc van hanh thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu bac) or (tu san)) ky nang o lai. ((hieu vien) OR (thieu nien)) cao duc van hanh thai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu bac) or (tu san)) ky nang o lai. ((hieu vien) OR (thieu nien)) cao duc van hanh thai cua tre*.