First documentation I found was in the South Pacific air war in the '40s.
Both (in the manner of their age) were extremely casual about documentation and acknowledgment.
This is particularly true of American colonial history where the documentation often is extremely full.
The documentation of this work is far thinner than for the Thames Tunnel.
The teaching of Germany's poets, prophets, professors, and preachers; a documentation.
So I think it would be normal that they would provide him with documentation.
Unfortunately, documentation of the case is almost wholly one sided, since his biggest publicizer was Mushet himself.