Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
dang xay » dang van, van xay
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
sach ky » sac ky, sach y, sach ty
hai tuc » thai tuc, hai cuc, thai thuc
va hanh » va thanh, va danh, ban hanh
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va hai » van hai, va chai, va khai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky ((nang xa) or (dang xay)) hoi. hieu va hai tuc ((va hanh) OR (van hanh)) va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang xa) OR (dang xay)) hoi. hieu va hai tuc ((va hanh) OR (van hanh)) va su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((nang xa) or (dang xay)) hoi. hieu va hai tuc ((va hanh) OR (van hanh)) va su triet".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang xa) or (dang xay)) hoi. hieu va hai tuc ((va hanh) OR (van hanh)) va su triet*.