Ronald S. Calinger, Leonhard Euler: Mathematical Genius in the Enlightenment , Princeton/Oxford: Princeton University Press 2016. xvii, 667 S., $ 55,00. ISBN 978‐0‐691‐11927‐4. Franz Lemmermeyer, Martin Mattmüller (eds.), Correspondence of Leonhard Euler with Christian Goldbach , 2 vol., (Leonhard Euler, Opera Omnia, Series quarta A : Commercium epistolicum 4) Basel: Birkhäuser 2015. xii, 1248 S., $ 359,00. ISBN 978‐3‐0348‐0879‐8 ..