Perhaps you should try some spelling variations:
nang khoa » hang khoa, dang khoa, nang hoa
nam thuc » nam thuoc, am thuc, nam thu
khoa hoi » khoan hoi, khoa hoc, khoa doi
su triet » su viet, ve triet
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
hanh ve » hanh vi, hanh va, hanh kem
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach ty
hieu he » hieu ve, hiem he, hieu le
su tien » su kien, su hien, tu tieng

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 nang khoa hoi. ((hieu he) or (hieu van)) nam thuc va hanh ve ((su triet) or (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang khoa hoi. ((hieu he) OR (hieu van)) nam thuc va hanh ve ((su triet) OR (su tien)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang khoa hoi. ((hieu he) or (hieu van)) nam thuc va hanh ve ((su triet) or (su tien))*.