Naming Infinity: A True Story of Religious Mysticism and Mathematical Creativity - by Loren Graham and Jean-Michel Kantor (Publisher: Belknap Press; 1st edition, March 31, 2009).
A topical review (in romanian) - around the ideas in a 2006 paper of Graham and Kantor - in Sinapsa Nr. 1, 37-46, 2008 ("Infinit, numiri, descoperire – o perihoreză a cunoaşterii. O incursiune în istoria ştiinţei" by Florin Caragiu and Mihai Caragiu).
The new book brings into the open an important chapter in the History of Mathematics and the grounds of the creativity manifested in the Russian School of Mathematics around the beginning of the 20th century.