Gerd Biegel has written:

'6. Februar 1794' -- subject(s): Braunschweigs Stiftung zum Andenken des 6ten Februars 1794, History

'Leonhard Euler, 1707-1783' -- subject(s): Science, Mathematicians, Biography, History

'Carl Friedrich Gauss'

Leonhard Lapin has written:

'Leonhard Lapin'

Leonhard Euler (after whom it was named).

Leonhard Euler (after whom it was named).

Leonhard Euler (after whom it was named).

Leonhard Euler (after whom it was named).

Mark Leonhard has written:

'Leonhard' -- subject(s): Exhibitions, Portrait photography

Karl Leonhard died in 1988.