Maryanne Conheim, "Firm buys historic Phila. photos," The Philadelphia Inquirer (Sept. 27, 1978).
Harry S. Silcox, Jennings' Philadelphia: The Life of a Philadelphia Photographer William Nicholson Jennings (1860-1946) (Philadelphia, 1993).

For further information regarding Jennings' work:

The Historical Society of Pennsylvania:

Franklin Institute: scrapbook of lightning photographs along with photographs of the Institute's collections