Kallen, W. L. J. Van der <br/><br/>
Infinitesimally central extensions of chevalley groups  / 

 - Berlin:  Springer-Verlag,  1973 
 - vii, 147p. Index 
 - Lecture notes in Mathematics   356 .
<br/><br/><label>Dewey Class. No.: </label>512  / K14.IC