1. BOOK REVIEWS - STEFAAN CAENEPEEL AND FREDDY VAN OYSTAEYEN EDITORS, HOPF ALGEBRAS IN NONCOMMUTATIVE GEOMETRY AND PHYSICS, PURE AND APPLIED MATHEMATICS; VOL. 239, MARCEL DEKKER, NEW YORK, 2005, 320 PP., ISBN 0-8247-5759-9.. Authors: ANDREI MARCUS.2. BOOK REVIEWS - STEFAAN CAENEPEEL AND FREDDY VAN OYSTAEYEN EDITORS, HOPF ALGEBRAS IN NONCOMMUTATIVE GEOMETRY AND PHYSICS, PURE AND APPLIED MATHEMATICS, VOL. 239, MARCEL DEKKER, NEW YORK, 2005, 320 PP., ISBN 0-8247-5759-9.. Authors: ANDREI MARCUS.3. RESTRICTION TO SUBGROUPS AND SEPARABILITY. Authors: ANDREI MARCUS.4. BOOK REVIEWS: LLUÍS PUIG EDITORS, FROBENIUS CATEGORIES VERSUS BRAUER BLOCKS. THE GROTHENDIECK GROUP OF THE FROBENIUS CATEGORY OF A BRAUER BLOCK. PROGRESS IN MATHEMATICS 274. BIRKHÄUSER BASEL-BOSTON-BERLIN, 2009, 498 P., ISBN: 978-3-7643-9997-9/HBK; ISBN. Authors: ANDREI MARCUS.