Create table error

Dear group,
Could you please suggest if my sql syntax is wrong for
creating the table:
my sql statements:
create table EXPERIMENT
(
        exp_id          serial,
        exp_name        varchar(32)     not null,
        con_id          serial  references
contacts(con_id),
        exp_type        varchar(32)     not null,
        exp_desc        varchar(64),
        exp_pmid        integer(30)     not null,
        exp_rawdata_url varchar(32),
        constraint      experiment_pk primary
key(exp_id)
);


When I compile this I get the following error:
psql:/home/sk/temp/postgres/exp.sql:11: ERROR:  syntax
error at or near "(" at character 200

What is wrong with my code.

Please help.

SK

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around
http://mail.yahoo.com