Perhaps you should try some spelling variations:
doanh cua » doanh luan
va doanh » van doanh, vay doanh, va danh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cac dac » cac dan, cac dai, cac bac
dac va » duc va, day va, dat va
cua tu » cua tuc, cua su, cua cu

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 x) or (nang cao)) hoi. hieu va cac dac va doanh cua ((cua te) OR (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang x) OR (nang cao)) hoi. hieu va cac dac va doanh cua ((cua te) OR (cua tu))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang x) or (nang cao)) hoi. hieu va cac dac va doanh cua ((cua te) OR (cua tu))*".