Shaw et al. (2015). Bias in student survey findings from active parental consent procedures. British Educational Research Journal, 41(2), 229-243. DOI: 10.1002/berj.3137
Suter, W. N.,(2014). Research Bias and Control (Chapter 7). In Introduction to Educational Research: A Critical Thinking Approach. doi: 10.4135/9781483384443.n7
Suter, W. N., (2014). Sampling in Research (Chapter 8). In Introduction to Educational Research: A Critical Thinking Approach. DOI: 10.4135/9781483384443.n8