Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cuu tre » cau tren, cau treo
dinh vi » dinh ve, dinh viet, dinh tri
va dinh » van dinh, va kinh, va tinh
nam luc » nang luc, nhan luc, nam thuc
tu sach » thu sach, su sach, te sach
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
cua tre » cua te, cua triet, dua tren
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: tu sach y ((nang ma) OR (tang ma)) hoi. hieu van nam luc va dinh vi ((cuu tre) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang ma) OR (tang ma)) hoi. hieu van nam luc va dinh vi ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang ma) OR (tang ma)) hoi. hieu van nam luc va dinh vi ((cuu tre) or (cua tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang ma) OR (tang ma)) hoi. hieu van nam luc va dinh vi ((cuu tre) or (cua tre))*.