Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
vat hanh » vat thanh, van hanh, va hanh
su triet » su viet, su tien, ve triet
ky lang » ky nang, ky dang, ky tang
lang ha » long ha
hieu he » hieu ve, hiem he, hieu le
hanh ve » hanh vi, hanh va, hanh kem
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
ha hoi » hoa hoi, ha noi, xa hoi
he nam » ha nam, nghe nam
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 lang ha 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 lang ha hoi. hieu he nam thuc vat hanh ve ((su triet) OR (su kien)).
• Adding a wildcard symbol may retrieve word variants: tu sac ky lang ha hoi. hieu he nam thuc vat hanh ve ((su triet) or (su kien))*.