1. Ashworth NL, Chad KE, Harrison EL, Reeder BA, Marshall SC (2005) Home versus center based physical activity programs in older adults. Cochrane Database of Systematic Reviews, CD004017
2. Brach M, Nieder F, Nieder U, Mechling H (under review) Implementation of preventive strength training in residential geriatric care: a multi-centre study protocol with one year of interventions on multiple levels [ISRCTN55213782]
3. Chen HT (1990) Theory-driven evaluations. Sage, London
4. Chen HT (2005) Practical program evaluation. Assessing and improving planning, implementation, and effectiveness. Sage, London
5. Godlee F (2001) Publishing study protocols: making them visible will improve registration, reporting and recruitment. BMC News, Views 2:4