Perhaps you should try some spelling variations:
trinh cay » trinh cau, trinh may, trinh cac
soi viet » hoi viet, oi viet, noi viet
doi viet » dai viet, hoi viet, oi viet
cay dan » cac dan, ca dan, cay lanh
cac cay » ca cay, cac cam, cac cap
so viet » hoc viet
cac cau » cac mau, bac cau, ca cau
dan va » doan va, dan ca, ban va
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 cay dan va cac cay co ((soi viet) or (doi viet)) nam ) or ( cong trinh cay dan va cac cay co so viet nam ))) or ( cong trinh cay dan va cac cau do ((soi viet) or (doi viet)) nam ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((( cong trinh cay dan va cac cay co ((soi viet) OR (doi viet)) nam ) OR ( cong trinh cay dan va cac cay co so viet nam ))) OR ( cong trinh cay dan va cac cau do ((soi viet) OR (doi viet)) nam )).
• Adding a wildcard symbol may retrieve word variants: (((( cong trinh cay dan va cac cay co ((soi viet) or (doi viet)) nam ) or ( cong trinh cay dan va cac cay co so viet nam ))) or ( cong trinh cay dan va cac cau do ((soi viet) or (doi viet)) nam ))*.