https://test.blue.repub.idris.pub/ppl/1081/ List of Publications en https://test.blue.repub.idris.pub/pub/3401/ Fri, 01 Jan 1960 00:00:01 GMT <div>J. Haak</div> https://test.blue.repub.idris.pub/pub/3456/ Fri, 01 Nov 1963 00:00:01 GMT <div>J. Haak</div>