*Warwick, Christopher, "Ella: Princess, Saint and Martyr", Wiley, 2007 ISBN 0-470-87063-X*Zeepvat, Charlotte, "The Camera and the Tsars", Sutton Publishing, 2004, ISBN 0-7509-3049-7.
*Warwick, Christopher, "Ella: Princess, Saint and Martyr", Wiley, 2007 ISBN 0-470-87063-X*Zeepvat, Charlotte, "The Camera and the Tsars", Sutton Publishing, 2004, ISBN 0-7509-3049-7.