Alexander Koester, Ducks Resting on the Banks of a River Signed lower right: A Koester Oil on canvas (relined) 70 x 100 cm Private collection, Westphalia. - Lempertz auction 920, Cologne, 17.5.2008, lot 1445. - Private ownership, North-Rhine Westphalia. Ruth Stein und Hans Koester: Alexander Koester 1864-1932. Leben und Werk, Recklinghausen 1988, no. 707.