N. P Zuithoff, Y Vergouwe, M King, I Nazareth, E Hak, K. G Moons and M. I Geerlings
Family Practice 26 ( 4 ): 241 - 250 , 2009
E. A Molenaar, Y Vergouwe and D. E Grobbee
Family Practice 27 ( 2 ): 143 - 150 , 2010