This file is from Wikimedia Commons and may be used by other projects.
The description on its file description page there is shown below.
Summary
DescriptionWłodzimierz Ptak 2017-12 5.jpg
Polski: Włodzimierz Ptak, immunolog, mikrobiolog, profesor nauk medycznych, sportretowany w swoim domu w Krakowie. Ptak jest ubrany w sweter, który otrzymał w prezencie kilkadziesiąt lat wcześniej od swojego przyjaciela Richarda K. Gershona, z którym współpracował na Yale University.
English: Włodzimierz Ptak, Polish immunologist and microbiologist, portrayed in his house in Kraków, Poland. Ptak is wearing a sweater that he received several dozen years earlier as a gift from his friend Richard K. Gershon, with whom he worked at Yale University.
to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.