Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 1-6

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 7-14

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 15-30

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 31-33

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 34-42

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 43-61

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 62-70

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 71-95

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 96-98

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 99-455

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 467-495

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 496-502

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 503-523

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 524-534

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 535-545

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 546-552

Published in Proceedings of The American Philosophical Society, in 1921, in volume 60, issue 220, pages 553-559