If you are person who is working shutdowns, contract or project roles, often your referees are supervisors from each position worked. These supervisors are usually in the same situation as you, on a shutdown, contract or project, and just like you they move on when the job is complete. Some of them have company email addresses or mobile phones issued just for the duration of the gig. If you are not keeping in touch and checking details of your referees in this environment, then you are probably sabotaging your job applications, as a prospective employer / recruiter will be unable to contact your referee. For each job you apply for, check that your referees are still working where you last had contact with them. If they have moved on to a new role and you want to show how you are linked to them, you can add a line to your resume that states they were (formerly the …….), so the employer /recruiter will be able to map the connection.