Perhaps you should try some spelling variations:
trinh hoang » trinh hoan, minh hoang, trinh han
trinh cong » trinh dung
hoang dan » hoang dang, hoang van, hoang san
trinh co » trinh do, trinh hoa, trinh ky
moi viet » muoi viet, moi viec, hoi viet
cong dan » cong san, cong tan, huong dan
mai viet » thi viet
oi viet » hoi viet, o viet, cuoi viet
co dang » cao dang, co dan, co dong
bac cau » bach cau, ba cau, bac can
dang va » dang van, dang vat, hang va
va bac » van bac, va cac, va bai
ca cau » cac cau, can cau, cua cau
dan va » doan va, dan ca, ban va
do oi » do moi, do voi, do o
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 co dang va ca cau do oi viet nam ) or ((( cong trinh cong dan va bac cau do oi viet nam ) or ( cong trinh hoang dan va bac cau do ((moi viet) OR (mai viet)) nam ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( cong trinh co dang va ca cau do oi viet nam ) OR ((( cong trinh cong dan va bac cau do oi viet nam ) OR ( cong trinh hoang dan va bac cau do ((moi viet) OR (mai viet)) nam )))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( cong trinh co dang va ca cau do oi viet nam ) or ((( cong trinh cong dan va bac cau do oi viet nam ) or ( cong trinh hoang dan va bac cau do ((moi viet) OR (mai viet)) nam ))))".
• Adding a wildcard symbol may retrieve word variants: (( cong trinh co dang va ca cau do oi viet nam ) or ((( cong trinh cong dan va bac cau do oi viet nam ) or ( cong trinh hoang dan va bac cau do ((moi viet) OR (mai viet)) nam ))))*.