Mitropolskiy, Yu. A., et al. “Wilhelm Illich Fushchych (on His 60th Birthday)”. Ukrains’kyi Matematychnyi Zhurnal, vol. 48, no. 12, Dec. 1996, pp. 1587-8, https://umj.imath.kiev.ua/index.php/umj/article/view/5181.