Comparison of four handheld point-of-care ultrasound devices by expert users oleh Minh-Phuong T. Le, Lara Voigt, Robert Nathanson, Anna M. Maw, Gordon Johnson, Ria Dancel, Benji Mathews, Alvaro Moreira, Harald Sauthoff, Christopher Gelabert, Linda M. Kurian, Jenna Dumovich, Kevin C. Proud, Jessica Solis-McCarthy, Carolina Candotti, Christopher Dayton, Alexander Arena, Brandon Boesch, Saul Flores, Mark T. Foster, Nicholas Villalobos, Tanping Wong, Gabriel Ortiz-Jaimes, Michael Mader, Craig Sisson, Nilam J. Soni