Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
su triet » su viet, su tien, ve triet
dang xay » dang van, van xay
va thanh » gia thanh, va tinh, le thanh
cac tuc » cac toc, cac tu, cac tac
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
moi su » oi su, doi su, mai su

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

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