Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hieu van » hieu va, thien van, lieu va
tinh voi » trinh voi, tinh doi, binh voi
tu sach » thu sach, su sach, te sach
nang xa » lang xa, nang ma, mang xa
nam tuc » nam thuc, nam truc, nam tu
va tinh » may tinh
cua tre » cua te, cuu tre, dua tren
tuc va » thuc va, truc va, tuc xa

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 y ((nang xa) or (nang x)) hoi. hieu van nam tuc va tinh voi ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang xa) OR (nang x)) hoi. hieu van nam tuc va tinh voi ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang xa) or (nang x)) hoi. hieu van nam tuc va tinh voi ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang xa) or (nang x)) hoi. hieu van nam tuc va tinh voi ((cua tre) OR (cua triet))*.