Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
dau luan » dan luan, dat luan, khau luan
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
sach ky » sac ky, sach y, sach ty
lang xa » lang ha, lang van
van dau » van dao, phan dau
vi su » va su, ve su, ki su

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

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