Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
va triet » va thiet, va trien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
va hanh » va thanh, va danh, ban hanh
va hoc » van hoc
hai va » hai van, thai va, hoi va
nuoc » quoc, duoc, ngoc

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 xa) or (nang ma)) hoi. lieu va hoc nuoc ((va hanh) or (van hanh)) hai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. lieu va hoc nuoc ((va hanh) OR (van hanh)) hai va triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang ma)) hoi. lieu va hoc nuoc ((va hanh) or (van hanh)) hai va triet*.