Perhaps you should try some spelling variations:
hieu phan » phieu phan, lieu phan, hieu pham
phan dau » phan tu, hang dau
cua viet » ca viet, hoa viet, cua vat
ly hang » ly quang
dau luc » cau luc, dau luan, dau nuoc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
co hoi » co hoc, co loi
y hang » ty hang, yu hang, _ hang
luc va » duc va, tuc va, loc va

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 ((y hang) OR (ly hang)) co hoi. hieu phan dau luc va hanh vi ((cua tre) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y hang) OR (ly hang)) co hoi. hieu phan dau luc va hanh vi ((cua tre) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((y hang) OR (ly hang)) co hoi. hieu phan dau luc va hanh vi ((cua tre) or (cua viet))".
• Adding a wildcard symbol may retrieve word variants: su sach ((y hang) OR (ly hang)) co hoi. hieu phan dau luc va hanh vi ((cua tre) or (cua viet))*.