Perhaps you should try some spelling variations:
lang khoa » hang khoa, dang khoa, long khoa
khoa hoi » khoan hoi, khoa hoc, khoa doi
sach ky » sac ky, sach y, sach ty
te sach » toc sach
hieu ve » hieu va, hieu van
ky lang » ky nang, ky dang, ky tang
thuc va » thuc dan, thuc day
ve nam » he nam, va nam, le nam
vai su » van su, lai su, tai su

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

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky lang khoa hoi. hieu ve nam ((thuc va) OR (thuc vat)) hanh ((vai su) OR (va su)) triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky lang khoa hoi. hieu ve nam ((thuc va) or (thuc vat)) hanh ((vai su) OR (va su)) triet~".
• Adding a wildcard symbol may retrieve word variants: te sach ky lang khoa hoi. hieu ve nam ((thuc va) or (thuc vat)) hanh ((vai su) OR (va su)) triet*.