Perhaps you should try some spelling variations:
doanh luan » doanh nhan
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
van cac » van hac, van cau, van bac
sach ky » sac ky, sach y, sach ty
cua te » cua tu
tuc va » thuc va, truc va, tuc xa
xuc va » duc va, luc va, xac 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 ky nang ma hoi. hieu van cac ((xuc va) OR (tuc va)) ((doanh cua) or (doanh luan)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. hieu van cac ((xuc va) OR (tuc va)) ((doanh cua) OR (doanh luan)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ma hoi. hieu van cac ((xuc va) OR (tuc va)) ((doanh cua) or (doanh luan)) cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu van cac ((xuc va) OR (tuc va)) ((doanh cua) or (doanh luan)) cua te*.