Perhaps you should try some spelling variations:
trinh may » trinh ky, trinh han, trinh ly
soi viet » hoi viet, oi viet, doi viet
sai viet » san viet, mai viet, tai viet
may ban » may san, tay ban, may van
can cau » van cau, ban cau, ca cau
so viet » hoc viet
cac cap » cao cap, cac cam, cac cau
va can » va chan, va cao, va con
cau co » cau do, cac co, cay co
co soi » cot soi, co hoi, co loi
cap do » cau do
do sai » do dai, do hai, do mai

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