B. Woltzenlogel-Paleo:
"Contextual Natural Deduction";
in: "Proceedings of the Symposium on Logical Foundations in Computer Science (LFCS 2013)", S. Artemov et al. (ed.); Springer LNCS, Heidelberg, 2013, ISBN: 978-3-642-35721-3, 372 - 386.
http://dx.doi.org/10.1007/978-3-642-35722-0