Ferro A, Pellegrino T, Spinelli L, Acampa W, Petretta M, Cuocolo A. Comparison Between Dobutamine Echocardiography and Single-Photon Emission Computed Tomography for Interpretive Reproducibility. The American Journal of Cardiology. 2007 Oct;100(8):1239–44. doi: 10.1016/j.amjcard.2007.05.041.