It is important for you to prepare your list of references before you interview. When you ask an individual for permission to be listed as a reference, you should obtain that individual’s personal e-mail and personal cell phone or home phone number, so that you can locate them if they leave their current company.
Ideally, your reference list will include 3 past managers that you’ve worked for. Alternatively, you could include at least 1 past manager and two other individuals (such as co-workers, customers, and/or vendors) who are familiar with your technical work expertise.
Putting "references available upon request" on your resume is no longer required and represents a waste of space on your resume. It is expected that if you are asked to interview for a position, you will provide a reference list if requested during the interview.