Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cam thuc » am thuc, nam thuc, cam thu
va hanh » va thanh, va danh, ban hanh
doi cua » dai cua, hoi cua, dong cua
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
va cam » va cham, va cac, va cao
sai ky » sac ky
cua te » cua tu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) or (sai ky)) nang xa hoi. hieu va cam thuc ((va hanh) OR (van hanh)) doi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sai ky)) nang xa hoi. hieu va cam thuc ((va hanh) OR (van hanh)) doi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sai ky)) nang xa hoi. hieu va cam thuc ((va hanh) OR (van hanh)) doi cua te".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sai ky)) nang xa hoi. hieu va cam thuc ((va hanh) OR (van hanh)) doi cua te*.