Kleinblatt is closed on those holidays (2020):

      1st of January New year
     8th of April till 16th of April Pessah (jewish easter)
   29th of May and 30th of May  Shavouoth (jewish pentecost)
     1st of August till 23rd of August yearly holidays
   19th of  September till 20th September Rosh hashana (jewish newyear)
   28th of  September Yom kippoer (day of reconciliation)
  3rd of October till 4th of October Soekoth (feast of tabernacles)
  10th of October till 11th October Simchat torah (feast of the bible)