O thou who art firm in the Covenant! Praise be to God that thou art firm in the Covenant and attracted to the Love of God
BBBD.Meinhard, Alexander. Briefen und Botschaften an die Baha’i, in Deutschland und weitere deutschsprachige länder. Private Printing, 2021. Letters and messages to Bahá’ís in Germany and other German-speaking countries
BBBD.331
Not yet online
DAS.Diary notebooks and letters of Mirza Ahmad Sohrab, Dec. 1912 – Jun. 1915. English and Persian diary notebooks and letters held in the U.S. National Bahá’í Archives. Often quoted in other sources such as SW. Catalog entries are indexed by date and include only the English notebooks and letters. Letters from 1 Jul 1913 through 19 Oct. 1914 found here: https://bahai-library.com/sohrab_diary_letters_1913-1914