Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, can thuc
dang mam » dang nam, dang mau, dang mat
cua tre » cua te, cuu tre, cua triet
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
cam thu » nam thu, cac thu, ca thu
hieu ve » hieu va, hieu van
dang ma » dang mau, dang mat, tang ma
sac ky » cac ky, sai ky
va cua » va chua, via cua, ca cua
te sac » te sach, te cac, te san

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

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