On 2{PFA}s and the Hadamard quotient of formal power series
Marcella Anselmo, Alberto Bertoni · Bulletin of the Belgian Mathematical Society - Simon Stevin · 1994
We present the main results on 2PFA's and on the Hadamard quotient of formal power series, the connection between the two notions being a result stating that the event defined by a 2PFA is the Hadamard quotient of two rational power series.