Perhaps you should try some spelling variations:
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
cam duc » cam xuc, cao duc, pham duc
hieu va » lieu va, hieu qua
sach ty » sach y, sach tu, sach thu
hieu ve » hieu van
ty sang » ty xang, ty hang, duy sang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, ma hoa, me hoi
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty sang ((ma hoi) or (xa hoi)). ((hieu ve) or (hieu va)) cam duc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty sang ((ma hoi) OR (xa hoi)). ((hieu ve) OR (hieu va)) cam duc va hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ty sang ((ma hoi) or (xa hoi)). ((hieu ve) or (hieu va)) cam duc va hanh vi cua tre*.