Perhaps you should try some spelling variations:
sach doi » sach hoi, sach moi, sach dao
doi nang » dai nang, hoi nang, voi nang
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
nang co » nang cao, nang doc, nang noi
thu van » thuc van, thuy van, tu van
co hoi » co hoc, co loi
di cua » dai cua, doi cua, de cua

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 doi nang co hoi. hieu van nam thu van hanh ((di cua) or (hoi chuc)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach doi nang co hoi. hieu van nam thu van hanh ((di cua) OR (hoi chuc)) viet.
• Adding a wildcard symbol may retrieve word variants: tu sach doi nang co hoi. hieu van nam thu van hanh ((di cua) or (hoi chuc)) viet*.