https://www.sil.org/resources/archives/61010
https://www.sil.org/resources/archives/61488
But this site appears to have no download link (or purchase link). Am I missing something obvious? Is it easy to access somewhere, or is this one of those "You need need to purchase a plane ticket and fly to the U.S. and dig around in the dusty basement of a library" to find it".

Thanks!