Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
su triet » su viet, su tien, ve triet
lang hoa » hang hoa, lang ha, nang hoa
vat hanh » vat thanh, van hanh, va hanh
hieu he » hieu ve, hiem he, hieu le
hanh ve » hanh vi, hanh va, hanh kem
hoa hoi » khoa hoi, hoa hoc, hoa doi
he nam » ha nam, nghe nam
sac ky » cac ky
kien » bien, vien, tien

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sac ky) OR (sai ky)) lang hoa hoi. hieu he nam thuc vat hanh ve ((su triet) or (su kien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sac ky) OR (sai ky)) lang hoa hoi. hieu he nam thuc vat hanh ve ((su triet) OR (su kien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sac ky) OR (sai ky)) lang hoa hoi. hieu he nam thuc vat hanh ve ((su triet) or (su kien))".
• Adding a wildcard symbol may retrieve word variants: tu ((sac ky) OR (sai ky)) lang hoa hoi. hieu he nam thuc vat hanh ve ((su triet) or (su kien))*.