- Created by: Todd Whitesides
- Added: 25 Feb 2016
- Find a Grave Memorial 158611443
Find a Grave, database and images (https://www.findagrave.com : accessed ), memorial page for Siemowit Piast of Masovia IV (unknown–21 Jan 1426), Find a Grave Memorial no. 158611443, citing Plock Cathedral, Płock, Miasto Płock, Mazowieckie, Poland ; Maintained by Todd Whitesides (contributor 47553735) .