sentences:  Beginning in 1922 he had made correspondences with Albert Schweitzer, which resulted in pronounced opinions concerning the demands which had to be made on the organ.Dirk Andries Flentrop (1910-2003), son of Hendrik and Christina Anna Dekker, took control of the company in 1940.Important organs, such as that of Hans van Covelen in the large church at Alkmaar, and the Schnitger organs in the large church at Zwolle and the Laurenskerk in Alkmaar, were restored.