Michael S Kramer, Richard M Martin, Jonathan A C Sterne, Stanley Shapiro, Mourad Dahhou, Robert W Platt et al
Kramer M S, Martin R M, Sterne J A C, Shapiro S, Dahhou M, Platt R W et al.
The double jeopardy of clustered measurement and cluster randomisation
BMJ 2009; 339 :b2900
doi:10.1136/bmj.b2900