@ARTICLE{Gutkin20132394,
doi = {http://dx.doi.org/10.1016/j.laa.2012.10.043},
title = {{J}oint numerical ranges, quantum maps, and joint numerical shadows},
url = {http://www.sciencedirect.com/science/article/pii/S0024379512007732},
journal = {Linear Algebra and its Applications},
author = {Eugene Gutkin and Karol \.Zyczkowski},
volume = {438},
year = {2013},
pages = {2394 - 2404},
arxiv = {http://arxiv.org/abs/1207.1227},
number = {5},
keywords = {Joint numerical range},
issn = {0024-3795}
}