Smirnova, L.N..  <br/><br/>
Snury i provoda svjazi /  
Smirnova L.N., Razuvaeva A.N., Panov B.M.. 
 - Moskva :   Svjaz',   1969. 
 - 61 s.;   24 cm. 
 - Mathematics and its Applications .
 - Mathematics and its Applications .