Published in Proceedings of the Washington Academy of Sciences, in 1900, in volume 2, pages 83-109

Published in Proc Washington Academy of Sciences, in 1900, in volume 2, pages 133-156

Published in Proceedings of The Washington Academy of Sciences, in 1900, in volume 2, pages 157-159

Published in Proceedings of the Washington Academy of Sciences, in 1900, in volume 2, pages 203-246

Published in Proceedings of the Washington Academy of Sciences, in 1900, in volume 2, pages 367-388

Published in Proceedings of the Washington Academy of Sciences, in 1900, in volume 2, pages 389-464

Published in Proceedings of the Washington Academy of Sciences, in 1900, in volume 2, pages 513-517

Published in Proceedings of the Washington Academy of Sciences, in 1900, in volume 2, pages 523-537

Published in Proceedings of the Washington Academy of Sciences, in 1900, in volume 2, pages 631-649

Published in Proceedings of the Washington Academy of Sciences, in 1900, in volume 13, pages 157