A functional chemical buffer is standardly prepared by combining a weak acid and its conjugate base (or a weak base and its conjugate acid), which is a fundamental chemical principle requiring no external citation.
A functional chemical buffer is standardly prepared by combining a weak acid and its conjugate base or a weak base and its conjugate acid.
The claim states a fundamental definition of buffer preparation in chemistry (combining a weak acid/base pair). This is common knowledge directly observable in standard chemical education and practice, requiring no external citation from the retrieved papers.