Reichinstein also wrote a biography of Einstein, "Albert Einstein sein Lebensbild und seine Weltanschauung" (which roughly translates as Albert Einstein: His Life and Worldview) that came out prior to 1936. Apparently it was written and possibly self-published in 1932, which led to Einstein writing to Reichinstein that

Wenn Sie dieses Manuskript irgendwo und irgendwie veröffentlichen, dann ist es zwischen uns für immer aus.

Google Translate renders this as:

If you publish this manuscript anywhere, in any way, then it's over between us forever.

i.e. strongly asking him not to publish the manuscript. Reichinstein then proceeded to publish the book in Prague in 1934. The relevant letter from Einstein to Reichinstein is dates May 26, 1932 and has been made available by the ETH Zurich Library's "Einstein Online" collection, specifically in the section on The Time in Berlin (1914-1933) along with several other letters to Reichinstein, Hermann Weyl, and others.