I have a question on a book which its last edition was published about 50 years ago and its author died about 47 years ago. Now it is out of print. The last edition of the book I am interested was translated to English (in 1965). I have sent email to its publisher about this book, but I didnt receive any answer. I also searched this book in the publisher's website, but I didnt find it. I also mention that I cant find its translator.
I have found the electronif file of the book in a website which allows users to download many books from it illegally (that is without any permission from the actual publishers).
My question is: Can I use that illegal electronic file of the book for self study ?
I put the information of the book below:
Title: Cardinal and Ordinal Numbers
Second Edition Revised 1965
Author: Wacław Sierpiński
Translated from Polish by: Janina Smólska
Publisher: PWN-Polish Scientific Publishers