21. ISBN: 9780393903850
Solution Manual of UNDERSTANDING OUR UNIVERSE
(1st Edition) written by George Blumenthal, Bradford
Smith, Stacy Palen, Laura Kay.
24. ISBN: 9780470419977
Solution Manual of MATERIALS SCIENCE AND ENGINEERING
AN INTRODUCTION (8th Edition) written by William D.
Callister & Jr. David G. Rethwisch.