Sent from Toronto, 1957. Handwritten postcard by Erdős. Signed by Erdős and six fellow mathematicians. Trace of folding and creasing. With a brown stain to upper edge, no effect on legibility. Overall in very good condition.. Handwritten postcard by Erdős. Signed by Erdős and six fellow mathematicians. 140 × 85 mm. Two lines of handwritten greetings in Erdős's hand, sent to his doctoral advisor Lipót Fejér (1880-1959). Beside Erdős the postcard is signed by fellow mathematicians: Nicholas D. Kazarinoff (1929-1991), Paul T. Bateman (1919-2012), Melvin Henriksen (1927-2009) , George G. Lorentz (1910-2006), Karl Longin Zeller (1924-2006) and Elias Zakon (1908-1991).