Hasselbach, Wilhelm Emeritus Group Biophysics, Max Planck Institute for Medical Research, Max Planck Society;
http://www.jbc.org/content/243/21/5656.full.pdf (Any fulltext)
Hasselbach, W., & Murphy, R. A. (1968). Calcium ion-dependent myofibrillar adenosine triphosphatase activity correlated with the contractile response. The Journal of Biological Chemistry, 243, 5656-5662.