Gray, A. (1857). Gray, Asa Oct. 20, 1857 [Gray to A. Grisebach] [copy]. Zenodo.
Cita Chicago (17th ed.)Gray, Asa. Gray, Asa Oct. 20, 1857 [Gray to A. Grisebach] [copy]. Zenodo, 1857.
Cita MLA (9th ed.)Gray, Asa. Gray, Asa Oct. 20, 1857 [Gray to A. Grisebach] [copy]. Zenodo, 1857.
Atenció: Aquestes cites poden no estar 100% correctes.