There are claims that Niels Bohr left a letter explaining why Lattes wasn't awarded the Nobel Prize. One source: The Oxford Companion to the History of Modern Science:
Powell received the Nobel Prize of 1950 for the discovery, an award that Latin Americans feel should have gone to Lattes. A letter from Niels Bohr, to be opened in 2012, supposedly explains Lattes's exclusion.
Is there any letter from Niels Bohr about this subject?