Nitsche, F., Jesche, A., Hieckmann, E., Doert, T., & Ruck, M. (2010). Structural trends from a consistent set of single-crystal data of RFeAsO (R=La, Ce, Pr, Nd, Sm, Gd, and Tb). Physical Review B, 82(13): 134514, pp. 134514-1-134514-8. doi:10.1103/PhysRevB.82.134514.