On the non-unitarity of the Bogoliubov transformation due to the quasiparticle space truncationJ. Dobaczewski, P. J. Borycki, W. Nazarewicz and M. StoitsovEur. Phys. J. A, 25 (2005) 541-542DOI: https://doi.org/10.1140/epjad/i2005-06-151-8