Perhaps you should try some spelling variations:
thuc dan » thuc hanh, hoc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
dinh vi » dinh ve, dinh viet, dinh tri
danh vi » hanh vi, danh di, danh va
hieu he » hieu ve, hiem he, hieu le
sach ky » sac ky, sach y, sach kem
may hoi » may thoi, tay hoi, mai hoi
sach ty » sach y, sach tu, sach thu
he nam » ha nam, nghe nam

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((sach ky) OR (sach ty)) mang may hoi. hieu he nam thuc dan ((danh vi) or (dinh vi)) hoa viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((sach ky) OR (sach ty)) mang may hoi. hieu he nam thuc dan ((danh vi) OR (dinh vi)) hoa viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((sach ky) OR (sach ty)) mang may hoi. hieu he nam thuc dan ((danh vi) or (dinh vi)) hoa viet".
• Adding a wildcard symbol may retrieve word variants: hoc ((sach ky) OR (sach ty)) mang may hoi. hieu he nam thuc dan ((danh vi) or (dinh vi)) hoa viet*.