Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
nam thuc » nam thuoc, am thuc, nam thu
sach doi » sach hoi, sach moi, sach dao
hieu van » hieu va, thien van, lieu va
doi nang » dai nang, hoi nang, voi nang
va danh » va dinh, va dan, va hanh
so sach » so sanh, bo sach, co sach
di cua » dai cua, doi cua, de cua
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach doi nang ((x hoi) OR (o hoi)). hieu van nam thuc ((va danh) or (gia thanh)) di cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach doi nang ((x hoi) OR (o hoi)). hieu van nam thuc ((va danh) OR (gia thanh)) di cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach doi nang ((x hoi) OR (o hoi)). hieu van nam thuc ((va danh) or (gia thanh)) di cua triet".
• Adding a wildcard symbol may retrieve word variants: so sach doi nang ((x hoi) OR (o hoi)). hieu van nam thuc ((va danh) or (gia thanh)) di cua triet*.