Perhaps you should try some spelling variations:
lang khoa » hang khoa, dang khoa, long khoa
nam thuc » nam thuoc, am thuc, nam thu
khoa hoi » khoan hoi, khoa hoc, khoa doi
su triet » su viet, ve triet
thanh ve » hanh ve, thanh va, thanh vien
va thanh » gia thanh, ban thanh, va tinh
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
su tien » su kien, su hien, tu tieng
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
hieu he » hiem he, hieu le, hieu hien
ky lang » ky nang, ky dang, ky tang

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