Perhaps you should try some spelling variations:
ban hanh » ban hang
sach thu » sach thue, sach thieu, sach tham
van phan » van phong, van thanh, luan phan
hieu van » hieu va, thien van, lieu va
hanh ki » hanh vi, hanh ky, hanh kien
lang xa » lang ha, dang xay, lang van
sach ty » sach y, sach tu, xach tay
nang xa » nang x, nang ma, mang xa
su viet » so viet
tu ban » thu ban, te ban
ki su » ky su

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