What was the name of the encyclical written in 1937?

Pope Pius XI published four encyclicals in 1937. They here follow in descending chronological order:

1. "Ingravescentibus Malis" - September 29th treating on the Rosary, addressed to the Universal Church.

2. "Nos Es Muy Conocida" - March 28th treating on the religious situation in Mexico, specifically addressed to the Mexican hierarchy.

3. "Divini Redemptoris" - March 19th treating on Atheistic Communism, addressed to the Universal Church.

4. "Mit Brennender Sorge" -March 14th treating on the Church and the German Reich, specifically addressing the German hierarchy. Of these, "Divini Redemptoris" was the most controversial and lauded, for it condemned Communism and has been a point of contention ever since.