Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
sach ty » sach y, sach tu, xach tay
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de 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: tu ((sach ty) or (sach thu)) nang x hoi. hieu va ((cao su) or (giao duc)) va hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) nang x hoi. hieu va ((cao su) OR (giao duc)) va hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach thu)) nang x hoi. hieu va ((cao su) or (giao duc)) va hanh di cua tre*.