On the non-unitarity of the Bogoliubov transformation due to the quasiparticle space truncation J. Dobaczewski, P. J. Borycki, W. Nazarewicz and M. Stoitsov Eur. Phys. J. A, 25 3 (2005) 541-542 Published online: 11 August 2005 DOI: 10.1140/epjad/i2005-06-151-8