What is the fine-grained topic of the following text: Moody's assigns B3 CFR to Riverdeep Interactive Learning USA, Inc.
MOODY'S HAS ASSIGNED A Baa2 RATING TO HOUGHTON MIFFLIN'S $150 MILLION 7.2% SENIOR UNSECURED NOTES DUE MARCH 15, 2011, AND AFFIRMS EXISTING RATINGS. Only return the topic.
Credit ratings for Riverdeep Interactive Learning USA, Inc. and Houghton Mifflin.