Perhaps you should try some spelling variations:
hieu quat » hieu qua, hieu luat, hieu suat
canh thuc » anh thuc, cach thuc, danh thuc
quat canh » luat canh, xuat canh, thuat canh
van hanh » van thanh, ban hanh, van anh
va hanh » va thanh, va danh, ban hanh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ra » nang ma, lang ra, nang ro
nang co » nang cao, nang doc, nang noi
vi cua » vai cua, di cua
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 co) or (nang ra)) hoi. hieu quat canh thuc ((va hanh) or (van hanh)) vi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang co) OR (nang ra)) hoi. hieu quat canh thuc ((va hanh) OR (van hanh)) vi cua tu.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang co) or (nang ra)) hoi. hieu quat canh thuc ((va hanh) or (van hanh)) vi cua tu*.