Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
sach hang » sach han, sach nang, khach hang
cong thai » hong thai, cong thanh, cong tac
nganh co » nganh cong, nganh hoa, nganh y
cong hai » cong ha, hoang hai, cong tac
vu sach » vu bach, vu khach
su sach » so sach

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( vu sach nganh co khi đong luc ) OR ( su sach hang ((cong thai) OR (cong hai)) đong luc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( vu sach nganh co khi đong luc ) or ( su sach hang ((cong thai) OR (cong hai)) đong luc ))~".
• Adding a wildcard symbol may retrieve word variants: (( vu sach nganh co khi đong luc ) or ( su sach hang ((cong thai) OR (cong hai)) đong luc ))*.