Habison, Peter (1998). "Astrometry and early astrophysics at Kuffner Observatory in the late 19th century". Acta Historica Astronomiae. 3: 93–94. Bibcode:1998AcHA....3...93H. ISSN0003-2670.
Habison, Peter (1998). "Astrometry and early astrophysics at Kuffner Observatory in the late 19th century". Acta Historica Astronomiae. 3: 93–94. Bibcode:1998AcHA....3...93H. ISSN0003-2670.