Perhaps you should try some spelling variations:
trinh cao » trinh chao, trinh cau, tinh cao
nuoc viet » ngoc viet, hoc viet
trinh co » trinh do, trinh cong, trinh hoa
toc viet » hoc viet, ngoc viet, thuc viet
bac cau » bach cau, bac can, bac cao
oi viet » hoi viet, o viet, cuoi viet
co dang » co dong, xo dang, do dang
cac dau » cac dan, cac du, cac dai
co nuoc » cho nuoc, co duoc, co nuoi
dang va » dang van, dang vat, hang va
cac cau » cac mau, ca cau, cac cam
cau cao » cu cao, cau tao, ca cao
cao toc » cac toc, cao hoc, cao tuoi
ba cau » ban cau, bo cau, va cau
ca cac » cua cac
co dan » co ban, ca dan
do oi » do moi, do voi, do o

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 ((bac cau) OR (ba cau)) do oi viet nam ) or ((( cong trinh co dan ca cac dau co nuoc viet nam ) or ( cong trinh cao dang va cac cau cao toc viet nam ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( cong trinh co dang va ((bac cau) OR (ba cau)) do oi viet nam ) OR ((( cong trinh co dan ca cac dau co nuoc viet nam ) OR ( cong trinh cao dang va cac cau cao toc viet nam )))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( cong trinh co dang va ((bac cau) OR (ba cau)) do oi viet nam ) or ((( cong trinh co dan ca cac dau co nuoc viet nam ) or ( cong trinh cao dang va cac cau cao toc viet nam ))))".
• Adding a wildcard symbol may retrieve word variants: (( cong trinh co dang va ((bac cau) OR (ba cau)) do oi viet nam ) or ((( cong trinh co dan ca cac dau co nuoc viet nam ) or ( cong trinh cao dang va cac cau cao toc viet nam ))))*.