Coba Ritsema ( 1876 - 1961 ) was a Dutch painter. Coba Ritsema s works have been put up for auction numerous times, with realized prices surpassing estimated prices, varying from 8305.44 USD for A PORTRAIT OF THE MOTHER OF THE ARTIST in 2003 to 13289.56 USD for Staand meisje op de rug gezien in 2004 , based on the size and medium of the artwork.