Perhaps you should try some spelling variations:
doanh than » doanh thanh, doanh nhan, doanh phan
nang mai » nang ma, nang tai, lang mai
mai khoi » mai khoa, tai khoa, cac khoi
hieu van » hieu va, thien van, lieu va
van chat » cao chat
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
than su » nhan su, tan su, than so
mac va » mac ca, tac va, bac va
ac va » tac va, bac va, rac va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang mai khoi. hieu van chat ((((ac va) OR (mac va))) or (duc va)) doanh than su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang mai khoi. hieu van chat ((((ac va) OR (mac va))) OR (duc va)) doanh than su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang mai khoi. hieu van chat ((((ac va) OR (mac va))) or (duc va)) doanh than su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang mai khoi. hieu van chat ((((ac va) OR (mac va))) or (duc va)) doanh than su triet*.