Stefan Wirz--I just visited your website...very nice!

You asked for some additional input on the albums. I have found some album dates you might be able to use:
terrea lea - 1970 (I have this LP)
Conversations with the Heart - ca. 1966
At the Garret - ca. 1961 (I have this LP)
Singing Guitar: Folk Songs - 1957

In addition to the albums I own as noted above, I have a copy of 'Folk Songs and Ballads'.
I note on the Garret website there is a CD available of many of her songs.