A (nearly complete) collection of
BBC Year Books may be viewed via this archive of Radio History.
Although predominantly American, there are numerous items from other countries.
One section is devoted to BBC Year Books. They are viewed in pdf format, beware- they will be large files!
Here is the link for the BBC Year Book Section, and
here is the general index page.
The index includes such items as "Wireless World" going back to 1911, and its forerunner The Marconigraph (1911- 1913).
The American site:-
"Americanradiohistory.com" incorporates "CommonwealthRadioHistory.com".
The site is always on the look-out for contributions to fill the occasional gaps in the collection.