Dear Group, I'd appreciate help with information about NowySacz records:

In the KehilaLinks web page for Nowy Sacz, there is a list of
residents that used to live in the city.
The title of the list is: "A List of 4,232 Jewish Residents of Nowy
Sacz – Compiled by William Leibner".
I'm investigating two names on this list - Ignacy and Jerzy WOLFSTAL.
The source for the information about them is therein said to be
"Personal Letters/Interviews".

MY QUESTION
-- Can anyone please point me to these "Personal Letters/Interviews"
used in compiling this Nowy Sacz resident list?
(any insight about the surname WOLFSTHAL in that Nowy Sacz will be
of course very helpful).

For reference, the links are:
KehilaLinks web page ---- https://kehilalinks.jewishgen.org/Nowy_Sacz/
List of residents ----
http://www.shtetlinks.jewishgen.org/Nowy_Sacz/residents.xls

Thanks in advance - Yaron Wolfsthal (yaron.wolfsthal@...