Certificate No. 1, Piel Bros, Herman Petersen, 29 March 1898.
Certificate No. 7, Piel Bros., Michael Piel, 1 April 1898.
Certificate No. 17, Piel Bros, Maria Piel, 1 September 1915.
Certificate No. 27, Piel Bros., Arthur Piel, Walter Piel, Richard S. Newcombe, Trustees of Sophia Piel, 14 May 1924.
