Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
cau thuc » cau truc, cuu thuc, can thuc
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach kem
hanh de » hanh ve, hanh kem
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
sach ty » sach y, sach tu, sach thu
de cua » le cua, te cua, dieu cua

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

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