Perhaps you should try some spelling variations:
trinh tu » trinh ky, trinh do
trinh ca » trinh cau, trinh cua, trinh cac
cac nam » bac nam, cac cam, cac ham
so viet » hoc viet
cac cay » ca cay, cac cam, cac cap
ca dan » cac dan, ca dao
dan va » doan va, dan ca, ban va
nam co » nam cao, nam bo, nam so
tu dan » tuc dan, tu ban, cu dan
cay co » cac co, tay co, cay cong

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