Matrix-free constructions of circulant and block circulant preconditioners. - Chao Yang 001; Esmond G. Ng; Pawel A. Penczek (Numer. Linear Algebra Appl., 2004)

Ab initio cryo-EM structure determination as a validation problem. - Pawel A. Penczek; Francisco J. Asturias (ICIP, 2014)