Además de la correspondencia de Einstein con su novia Mileva Marić resulta extraordinariamente interesante la intercambiada con sus amigos Michele Besso (durante 52 años) y con Max Born (durante 39 años), por el cruce de ideas científicas y de pensamientos en torno a sus circunstancias personales.
In addition to Einstein's correspondence with his girlfriend Mileva Marić, the exchange maintained with his friends Michele Besso (for 52 years) and with Max Born (for 39 years) is extraordinarily interesting, discussing scientific ideas and thoughts about their personal circumstances.