I have a some of these PMG course of technical instruction books, dated 1949-1964. My father used these during his PMG / Telecom career, ca. 1938-1977, finishing as the STOIC running the telephone exchange in a rural city in Victoria.
Radio 1, Radio 2
Telephony 1, 2, 3, 4
Long Line Equipment 2, 3
Heat, Magnetism & Electricity
Drawing for Telecommunication
Applied Electricity 2 (very good on DC & AC theory)
Australian Post Office Workshops Data Handbook
I drooled over these from about 10 years old, in early 1970s. These books and Electronics Australia mag got me into the hobby. Still going.