Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
hanh de » hanh ve, hanh kem
hanh di » hanh vi, hang di, danh di
thuc va » thuc vat, thuc dan, thuc day
van cam » van nam, van lam, van cau
sach ky » sach y, sach ty, sach kem
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
sac ky » cac ky, sai ky

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