Perhaps you should try some spelling variations:
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, lang van
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
han tri » han tai, van tri, thanh tri
va han » va phan, van han, va hanh
cua su » qua 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 ky ((nang xa) or (((lang xa) OR (dang xay)))) hoi. hieu van cau duc va han tri cua su~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang xa) OR (((lang xa) OR (dang xay)))) hoi. hieu van cau duc va han tri cua su.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang xa) or (((lang xa) OR (dang xay)))) hoi. hieu van cau duc va han tri cua su".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang xa) or (((lang xa) OR (dang xay)))) hoi. hieu van cau duc va han tri cua su*.