Perhaps you should try some spelling variations:
trinh cac » trinh cau, trinh chat, trinh chao
trinh cay » trinh cau, trinh may, trinh bay
soi viet » oi viet, doi viet, noi viet
hoi viet » hai viet, oi viet, thai viet
cac ban » cac dan, cac van, can ban
cac cay » ca cay, cac cam, cac cau
cay dan » cac dan, ca dan, cay lanh
so viet » hoc viet
cac cap » cao cap, cac cam, cac cau
cay co » cac co, tay co, cay cong
dan va » doan va, dan ca, han va
cap do » cau do

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 cac ban va cac cay co ((soi viet) OR (hoi viet)) nam ) or ( cong trinh cay dan va cac cay co so viet nam ))) or ( cong trinh cay dan va cac cap do ((soi viet) OR (hoi viet)) nam ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((( cong trinh cac ban va cac cay co ((soi viet) OR (hoi viet)) nam ) OR ( cong trinh cay dan va cac cay co so viet nam ))) OR ( cong trinh cay dan va cac cap do ((soi viet) OR (hoi viet)) nam )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((( cong trinh cac ban va cac cay co ((soi viet) OR (hoi viet)) nam ) or ( cong trinh cay dan va cac cay co so viet nam ))) or ( cong trinh cay dan va cac cap do ((soi viet) OR (hoi viet)) nam ))".
• Adding a wildcard symbol may retrieve word variants: (((( cong trinh cac ban va cac cay co ((soi viet) OR (hoi viet)) nam ) or ( cong trinh cay dan va cac cay co so viet nam ))) or ( cong trinh cay dan va cac cap do ((soi viet) OR (hoi viet)) nam ))*.