Downloading PostgreSQL source code version 7.1 through CVS

[Kuriakose, Cinu Cheriyamoozhiyil]

Hi all, 

Can anyone please tell me how to download the PostgreSQL-7.1 source code 
through CVS, i use the following set of commands to get the source code of 
postgreSQL.

1) cvs -d :pserver:address@hidden:/projects/cvsroot login
This command will do an initial login to the PostgreSQl repository.

2) cvs -z3 -d :pserver:address@hidden:/projects/cvsroot co -P pgsql
This will fetch the code, but the code that is fetched is the latest code.

Can anyone please tell me what command I have to use to download the source 
code For PostgreSQL-7.1.

Thanks in advance
Regards
Cinu Kuriakose