1. National Institute of Standards and Technology (NIST). (2010). SP 800-34 Rev. 1
Contingency Planning Guide for Federal Information Systems. Page 40 (Section 4.3.2). "Incremental backup—a copy of all files that have changed since the last full or incremental backup."
2. Carnegie Mellon University Information Security Office. (n.d.). Data Backup Options. Retrieved from https://www.cmu.edu/iso/governance/guidelines/data-backup.html. The guideline states
"Incremental Backup: Backs up only the data that has changed since the last backup (of any kind)."
3. Silberschatz
A.
Galvin
P. B.
& Gagne
G. (2018). Operating System Concepts (10th ed.). Wiley. In Chapter 12
Section 12.7.2
"Backup and Restore
" it is defined that "An incremental backup copies only the files that have changed since the last partial backup."