Birth year in: Zur Existenz eines ganz starken anthropischen Prinzips, https://books.google.ch/books?id=lGktIndUX3MC&pg=PP5&dq=1925+Lieth,+Helmut&hl=de&sa=X&ved=2ahUKEwjSwLGAtdb9AhUWgv0HHeWOAhYQ6AF6BAgHEAI#v=onepage&q=1925%20Lieth%2C%20Helmut&f=false & Death year in: Environmental Institute of Scientific Networks, https://www.eisn-institute.de/obituary/ (via Boris Heuer)