Perhaps you should try some spelling variations:
thieu bien » thieu nien, tieu bieu, hien bien
van hanh » van thanh, ban hanh, van anh
bien cac » vien cac, dien cac, bien ca
cua viet » ca viet, hoa viet, cua vat
sach ty » sach y, sach tu, sach thu
nang xa » lang xa, nang ma, mang xa
cac tuc » cac toc, cac tu, cac tac
va hanh » va thanh, va danh, ban hanh
tu sach » thu sach, su sach, te sach
vi cua » vai cua, di cua

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 ty ((nang xa) or (nang x)) hoi. thieu bien cac tuc ((va hanh) OR (van hanh)) vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (nang x)) hoi. thieu bien cac tuc ((va hanh) OR (van hanh)) vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang xa) or (nang x)) hoi. thieu bien cac tuc ((va hanh) OR (van hanh)) vi cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (nang x)) hoi. thieu bien cac tuc ((va hanh) OR (van hanh)) vi cua viet*.