Baxendale, R. W., & Baxter, R. W. (1977). A new fertile Schizaeaceous fern from Middle Pennsylvanian Iowa coal balls. University of Kansas.
Cita Chicago (17th ed.)Baxendale, R. William, i Robert W. Baxter. A New Fertile Schizaeaceous Fern from Middle Pennsylvanian Iowa Coal Balls. Kansas: University of Kansas, 1977.
Cita MLA (9th ed.)Baxendale, R. William, i Robert W. Baxter. A New Fertile Schizaeaceous Fern from Middle Pennsylvanian Iowa Coal Balls. University of Kansas, 1977.
Atenció: Aquestes cites poden no estar 100% correctes.