BioStor
 | Additions to the flora of Washington and vicinity, from April 1, 1884 to April 1, 1886 F H Knowlton (1886) Proceedings of The Biological Society of Washington 3: 106-132 |
 | A review of the fossil flora of Alaska, with descriptions of new species F H Knowlton (1894) Proceedings of The United States National Museum 17: 207-240 |