Johanna Martzy

Does anybody know what the sources were for the the Coup d’Archet LP versions of Johanna Martz's work? Were they made from the original master tapes? There is really no mention of that on their site and I'm very interested in getting them. I know that the Electric Recording Co. versions of those pressings are getting very high praise but I'm not willing to spend $480 per disc. Thanks in advance for any information: )