Perhaps you should try some spelling variations:
trinh tai » trinh toan, chinh tai
trinh han » trinh quan
trinh tu » trinh ky, trinh do
hoi viet » hai viet, oi viet, thai viet
soi viet » oi viet, doi viet, noi viet
cac ban » cac dan, cac van, can ban
cac cac » cac cach, ca cac, cac bac
tai dan » tai san, tai ban, thi dan
han dan » nhan dan, han danh, shan dan
cau nam » bau nam, cai nam, cu nam
so viet » hoc viet
va cau » van cau, va dau, va cao
nam co » nam cao, nam bo, nam so
co hoi » co hoc, co loi
cap co » tap co, cap do, cac co
tu dan » tuc dan, tu ban, cu dan
dan va » doan va, dan ca, ban va

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 tai dan va cac ((cap co) or (cap cho)) soi viet nam ) or ( cong trinh han dan va cau nam co hoi viet nam ))) or ( cong trinh tu dan va ((cac cac) or (cac ban)) co so viet nam ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((( cong trinh tai dan va cac ((cap co) OR (cap cho)) soi viet nam ) OR ( cong trinh han dan va cau nam co hoi viet nam ))) OR ( cong trinh tu dan va ((cac cac) OR (cac ban)) co so viet nam )).
• Adding a wildcard symbol may retrieve word variants: (((( cong trinh tai dan va cac ((cap co) or (cap cho)) soi viet nam ) or ( cong trinh han dan va cau nam co hoi viet nam ))) or ( cong trinh tu dan va ((cac cac) or (cac ban)) co so viet nam ))*.