Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dau luan » dan luan, dat luan, khau luan
su sach » so sach, vu sach
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
dau luc » cau luc, dau nuoc, dau luot
ly hang » ly quang
cua tre » cua te, cuu tre, cua triet
y hang » ty hang, yu hang, _ hang
co hoi » co hoc, co loi
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 ((y hang) or (ly hang)) co hoi. hieu van ((dau luc) OR (dau luan)) va danh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y hang) OR (ly hang)) co hoi. hieu van ((dau luc) OR (dau luan)) va danh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((y hang) or (ly hang)) co hoi. hieu van ((dau luc) OR (dau luan)) va danh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((y hang) or (ly hang)) co hoi. hieu van ((dau luc) OR (dau luan)) va danh vi cua tre*.