e-Source: Chapter 1 'Determining Appropriate Methods' by John B McKinlay
e-Source: Chapter 3 'Theory Development and Construction' by Stephen Turner
e-Source: Chapter 7 'A Reporting Checklist for Observational Studies' by Richard Berk
e-Source: Chapter 8 on 'Using Qualitative Methods to Study Health and Illness' by David Silverman
e-Source: Chapter 11 'Clinical Trials' by Duolao Wang and Ameet Bakhai
all at:
www.esourceresearch.org

Social research methods – Design
www.socialresearchmethods.net/kb/design.php

Experiment-resources.com – Types of Research Designs
www.experiment-resources.com/research-designs.html

Methods@manchester – experimental methods
www.methods.manchester.ac.uk/methods/experiments/index.shtml