Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su triet » su viet, ve triet
vat hanh » vat thanh, van hanh, va hanh
lang hoa » hang hoa, lang ha, nang hoa
nam thuc » nam thuoc, am thuc, nam thu
hanh ve » hanh vi, hanh va, hanh kem
sach ky » sach y, sach ty, sach kem
hoa hoi » khoa hoi, hoa hoc, hoa doi
su tien » su kien, su hien, tu tieng
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: tu ((sach ky) or (sac ky)) lang hoa hoi. hieu van nam thuc vat hanh ve ((su triet) or (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) lang hoa hoi. hieu van nam thuc vat hanh ve ((su triet) OR (su tien)).
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) lang hoa hoi. hieu van nam thuc vat hanh ve ((su triet) or (su tien))*.