Beckers, J. <br/><br/>
Invariace under conformal coordinate and point transformations 
/ J. Beckers and S. Sinzinkayo 
. - Amsterdam  : Elsevier Science Publishers, 1984
. - 372-383 p.  ; 24 cm. 
<br/><br/><label>Source: </label> Don 
<br/><br/><label>Universal Decimal Class. No.: </label>530.01