From Memoria sobre las virtudes y usos de la raiz de Purhampuy ó China Peruana, por Don Hipólito Ruiz ... ilustrada y aumentada por el licenciado Don Antonio Ruiz ... Madrid, Imprenta de Don José del collado. 1821.
Photostat reproduction (negative) from the copy in the Arnold Arboretum of Harvard University.
This is but a small portion of the letter addressed to Jaochim Roelants and does not include the discussion of Vesalius' exchange of letters with Sylvius, or the appended regimen, originally in Italian.