Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
cao hoc » cho hoc, chat hoc
va hanh » va thanh, va danh, ban hanh
su tien » su kien, su hien, tu tieng
y nang » ky nang, ly nang, v nang
va cam » va cham, va cac, va cao
ki su » ky su

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 y nang ((cao hoc) OR (co hoc)). lieu va cam thuc ((va hanh) OR (van hanh)) ki su tien~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((cao hoc) OR (co hoc)). lieu va cam thuc ((va hanh) OR (van hanh)) ki su tien".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((cao hoc) OR (co hoc)). lieu va cam thuc ((va hanh) OR (van hanh)) ki su tien*.