Perhaps you should try some spelling variations:
giao nguoi » gian nguoi, giap nguoi, giau nguoi
tac nguoi » toc nguoi, tay nguoi, thuc nguoi
thue giao » thue gia, thuyet giao, thuat giao
sach hoc » cach hoc, sach hoi, sach duoc
mach hoc » cach hoc, dich hoc, anh hoc
cac thue » cuc thue, cac thu, cach thuc
so cac » sao cac, so cap, o cac

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 hoc) OR (mach hoc)) tac nguoi ) or ( so cac thue giao nguoi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( thuoc ((sach hoc) OR (mach hoc)) tac nguoi ) OR ( so cac thue giao nguoi )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( thuoc ((sach hoc) OR (mach hoc)) tac nguoi ) or ( so cac thue giao nguoi ))".
• Adding a wildcard symbol may retrieve word variants: (( thuoc ((sach hoc) OR (mach hoc)) tac nguoi ) or ( so cac thue giao nguoi ))*.