Davies, D.: 'Shifting boundaries', Electronics Letters, 2012, 48, (23), p. 1439-1439, DOI: 10.1049/el.2012.3759 IET Digital Library, https://digital-library.theiet.org/;jsessionid=7lvjvaldd9bce.x-iet-live-01content/journals/10.1049/el.2012.3759