Perhaps you should try some spelling variations:
cach thuc » anh thuc, cac thu
cac thuc » cac thu, can thuc, cay thuc
day dang » da dang, dai dang, day dan
cua tre » cua te, cuu tre, cua triet
dang de » dang deo, dung de, dang do
hieu ve » hieu va, hieu van
de cua » le cua, te cua, dieu cua
sac ky » cac ky
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu ((sai ky) OR (sac ky)) nang x hoi. hieu ve ((cac thuc) or (cach thuc)) day dang de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sai ky) OR (sac ky)) nang x hoi. hieu ve ((cac thuc) OR (cach thuc)) day dang de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sai ky) OR (sac ky)) nang x hoi. hieu ve ((cac thuc) or (cach thuc)) day dang de cua tre".
• Adding a wildcard symbol may retrieve word variants: vu ((sai ky) OR (sac ky)) nang x hoi. hieu ve ((cac thuc) or (cach thuc)) day dang de cua tre*.