Valtonen, Erik <br/><br/>
Some results on commutative semitrivial ring extensions 
Erik Valtonen 
 - Stockholms  Univ. Stockholms  1989 
 - pag. dif  24 cm 
<br/><br/> Contine bibliogr. dupa capitole 
<br/><br/><label>ISBN: </label>917146736x