Longitudinal study as a research method - some resources

The following resources are on Longitudinal Study as a Research Method:

1. Basic description: http://en.wikipedia.org/wiki/Longitudinal_study
2. Description of Longitudinal Study: http://www.historylearningsite.co.uk/longitudinal_studies.htm
3. A related article that explains longitudinal study (pdf): http://www.uwpsychiatry.org/sls/Longitudinal%20research%20methodology.pdf