Here are various articles by RCA or authors who worked at RCA. Articles listed cchronologically.
Waller & Richards 1935 How to Use the Magic Eye Tube as a Service Instrument - How to make a "slide-back" voltmeter using the 6E5 magic eye tube. Meters work better.
RCA 1947 6AS7G Low Mu Twin Power Triode - Application Note from the Oct.-Dec. 1947 RCA Ham Tips magazine. Often-overlooked factors when using the 6AS7G as an audio power amplifier..
Hanchett Jr 1948 Fail-Safe Operation Electronic Control Circuits - Arranging thyratron control circuits so that circuit failures do not cause unwanted actions.