Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
van hanh » van thanh, ban hanh, van anh
va hanh » va thanh, va danh, ban hanh
cua tre » cua te, cuu tre, cua triet
sach ky » sach y, sach ty, sach kem
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
sac ky » cac ky, sai ky
di cua » dai cua, doi cua, de cua
ve cam » ve cham, ve cac, va cam

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