Avkir: This Midrash (rabbinic interpretive commentary) is named so because of the acronym at the end of the teachings: Amen, B'yamenu, Ken, Yehi, Ratzon (in our days, so be it). The Midrash Avkir was never printed and is not currently found in known manuscript collections. However, it is mentioned by ancient scholars, and the last one who saw and referenced it in print was Rabbi Azariah dei Rossi in his book "Me'or Einayim" (1577). The Yalkut Shimoni references it many times. Rabbi Shalom Buber collected the snippets from Midrash Avkir found scattered in the Yalkut and added his notes in "HaShachar" year 11, and also in a separate booklet (Vienna, 1873). See also "Yeri'ot Shlomo", an addition to "Rav Pe'alim" by Rabbi Azriel Hildesheimer (Warsaw, 1894). See also "Avkir" in the "Otzar Yisrael" encyclopedia.