The three references listed below were missing from the AMR Book Review (#7R12, AMR55(4) July 2002, pp. B65⋅B66) of the book Vibration of Strongly Nonlinear Discontinuous Systems (by VI Babitsky and VL Krupenin). We apologize to the reviewer, J Angeles, and to the reader for this omission.

Flu¨gge-Lotz I (1968), Discontinuous and Optimal Control, McGraw-Hill Book Co., McGraw-Hill Series in Modern Applied Mathematics, New York.
Pfeiffer F and Glocker Ch (1996), Multi-body Dynamics with Unilateral Contacts, Wiley-Interscience, New York.
Strang G (1988), Linear Algebra, Third Edition, Harcourt Brace Jovanovich College Publishers, Ft Worth.