“A sample is a small proportion of a population selected for observation and analysis.”

— C. R. Kothari & Gaurav Garg, Research Methodology: Methods and Techniques (4th ed., 2019) 

“Sampling is the process of selecting a sufficient number of elements from the population so that study of the sample and understanding of its properties would make it possible for us to generalize such properties to the population elements.”

— Uma Sekaran & Roger Bougie, Research Methods for Business: A Skill-Building Approach (9th ed., 2023)