Perhaps you should try some spelling variations:
trinh quan » trinh luat, trinh han
trinh ca » trinh cau, trinh cua, trinh cac
trinh tu » trinh ky, trinh do
hoi viet » hai viet, thai viet, cuoi viet
oi viet » o viet, cuoi viet, gioi viet
cac cam » cac cap, cac cau, cac cay
ca cac » cua cac, va cac
tu dan » tuc dan, tu ban, cu dan
dan va » doan va, dan ca, ban va
cac co » cac cong
va ca » va cac, va cao, va cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( cong ((trinh ca) or (((trinh quan) OR (tinh quang)))) dan va ((cac cam) or (cad cam)) co ((oi viet) or (hoi viet)) nam ) or ( cong trinh tu dan va ca cac co ((oi viet) or (hoi viet)) nam ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( cong ((trinh ca) OR (((trinh quan) OR (tinh quang)))) dan va ((cac cam) OR (cad cam)) co ((oi viet) OR (hoi viet)) nam ) OR ( cong trinh tu dan va ca cac co ((oi viet) OR (hoi viet)) nam )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( cong ((trinh ca) or (((trinh quan) OR (tinh quang)))) dan va ((cac cam) or (cad cam)) co ((oi viet) or (hoi viet)) nam ) or ( cong trinh tu dan va ca cac co ((oi viet) or (hoi viet)) nam ))".
• Adding a wildcard symbol may retrieve word variants: (( cong ((trinh ca) or (((trinh quan) OR (tinh quang)))) dan va ((cac cam) or (cad cam)) co ((oi viet) or (hoi viet)) nam ) or ( cong trinh tu dan va ca cac co ((oi viet) or (hoi viet)) nam ))*.