Job Foss - Military Service

Job is a direct ancestor of mine and I would like to know more about his military service in the Civil War. I've seen one secondary source that indicates that he served in both the 16th and 20th Maine regiments that fought in a number of battles in which more than 200 men died and an additional 200+ were injured. I'd like to find more sources that will confirm/validate his military service as a private.