Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
chat hoc » chat hoa, chat thom, cho hoc
tu sach » thu sach, su sach, te sach
cao tuc » dao tuc, cao duc, cao suc
va hanh » va thanh, va danh, ban hanh
su tien » su kien, su hien, tu tieng
hieu va » lieu va, hieu qua
ly nang » ly hang, ly vang, ly quang
va cao » va cac, va co, va dao
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 ((ly nang) OR (ky nang)) chat hoc. hieu va cao tuc ((va hanh) or (van hanh)) ki su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ly nang) OR (ky nang)) chat hoc. hieu va cao tuc ((va hanh) OR (van hanh)) ki su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ly nang) OR (ky nang)) chat hoc. hieu va cao tuc ((va hanh) or (van hanh)) ki su tien".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ly nang) OR (ky nang)) chat hoc. hieu va cao tuc ((va hanh) or (van hanh)) ki su tien*.