Vols. 1-2, 1820-21 v. 1, 1820 v. 2, late April 1821
Remarks
Regarding the date of vol. 2: in the introduction of the article in the journal Flora (4: 294, bottom. 21 May 1821, https://www.biodiversitylibrary.org/page/17476#page/296/mode/1up ), there is a statement at the beginning of the Review mentioning that vol. 2 of the book would be available to the public at the Ostermesse of the same year (‘Der zweite Theil der Reise durch Brasilien wird in der nächsten Ostermesse ausgegeben’ (= The second part of the book … will be given out at the next Easter mass (of the same year)); the Easter in 1821 was on 22 April. Internet Link: Vol. 1: https://archive.org/stream/gri_resisenachbra01wied#page/n3/mode/2up ; vol. 2: https://archive.org/stream/reisenachbrasili02wied#page/n3/mode/2up