Perhaps you should try some spelling variations:
hanh vai » hanh vi, hanh va, hanh tai
hieu van » hieu va, thien van, lieu va
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
cam tuc » cam xuc, cam tu, nam thuc
van cam » van nam, van lam, van cau
mai hoi » mai khoi, dai hoi, lai hoi
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
ma hoi » xa hoi, ma hoa, me hoi
tuc va » thuc va, truc va, tuc xa

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) or (cac ky)) tang ((ma hoi) OR (mai hoi)). hieu van cam tuc va hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (cac ky)) tang ((ma hoi) OR (mai hoi)). hieu van cam tuc va hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (cac ky)) tang ((ma hoi) OR (mai hoi)). hieu van cam tuc va hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (cac ky)) tang ((ma hoi) OR (mai hoi)). hieu van cam tuc va hanh vai cua tre*.