In a series of documents recently made public by the NSA there's also several volumes that deal with Axis SigInt which are extremely interesting to read.

They also contain tidbits about romanian cryptographic codes and reports on its decryption or partial decryption undertaken by Romania's allies ( yes, you read that right )

The documents can be searched through by simply using ctrl+f, not all results will pop up though due to the quality of the scans.

Eg keywords : Rumania, rumanian

http://www.nsa.gov/public_info/declass/eur...is_sigint.shtml