Onkel Feri is repeatedly mentioned in Gertrud Bortstieber's letters sent to her friend Laura Bíró Zsigmondné in Nové Mesto nad Váhom during the 1920s. Based on the content it seems that Onkel Feri is a close relative of Gertrud Bortstieber's mother, who is possibly also living in, or originating from, Nové Mesto nad Váhom. See also Gertrud Bortstieber's letters written to Laura Bíró Zsigmondé in the 2020 accruals to this fonds (series HU OSA 439-2-1).