Perhaps you should try some spelling variations:
lang van » dang van, tang van, hoang van
phan duc » pham duc, phan tu, phan dau
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
hieu ke » hieu kem, chieu ke, hieu ky
ke phan » ve phan, kenh phan, ke thang
va hanh » va thanh, va danh, ban hanh
kiem su » kiem thu, kiem sat, kiet suc

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 x) or (lang van)) hoi. hieu ke phan duc ((va hanh) OR (van hanh)) kiem su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang x) OR (lang van)) hoi. hieu ke phan duc ((va hanh) OR (van hanh)) kiem su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang x) or (lang van)) hoi. hieu ke phan duc ((va hanh) OR (van hanh)) kiem su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang x) or (lang van)) hoi. hieu ke phan duc ((va hanh) OR (van hanh)) kiem su triet*.