Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
nam xuc » cam xuc, nam xua, nam thuc
cuu tre » cau tren, cau treo
dinh vi » dinh ve, dinh viet, dinh tri
va dinh » van dinh, va kinh, va tinh
cua tre » cua te, cua triet, dua tren
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
y nang » ky nang, ly nang, v nang
xuc va » duc va, tuc va, luc va
ma hoi » mai hoi, xa hoi, ma hoa

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 hoi. ((hieu van) OR (hieu va)) nam xuc 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 hoi. ((hieu van) OR (hieu va)) nam xuc 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 hoi. ((hieu van) OR (hieu va)) nam xuc va dinh vi ((cuu tre) or (cua tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ma hoi. ((hieu van) OR (hieu va)) nam xuc va dinh vi ((cuu tre) or (cua tre))*.