Published in Proceedings of the Academy of Natural Sciences, Philadelphia, in 1919, in volume 71, pages 125-127

Published in Proceedings of the Academy of Natural Sciences, Philadelphia, in 1919, in volume 71, pages 55-120

Published in Proceedings of the Academy of Natural Sciences of Philadelphia, in 1919, in volume 71, pages 2-15

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1919, in volume 71, pages 317-323

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1919, in volume 71, pages 121

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1919, in volume 71, pages 206

Published in Proceedings of The Academy of Natural Sciences of Philadelphia, in 1919, in volume 71, pages 306-312