Perhaps you should try some spelling variations:
doanh cua » doanh luan
thu sach » tu sach, thuat sach, thuoc sach
va doanh » van doanh, vay doanh, va danh
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cao duc » dao duc, cao suc, giao duc
va cao » va cac, va co, va dao
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: thu sach ky ((nang x) or (nang cao)) hoi. hieu va cao duc va doanh cua ((cua te) OR (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang x) OR (nang cao)) hoi. hieu va cao duc va doanh cua ((cua te) OR (cua tu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((nang x) or (nang cao)) hoi. hieu va cao duc va doanh cua ((cua te) OR (cua tu))".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang x) or (nang cao)) hoi. hieu va cao duc va doanh cua ((cua te) OR (cua tu))*.