In case the author is here, you can find the Garland & Garland (1980) article on sci-hub.

And if link is allowed https://sci-hub.ru/https://doi.org/10.1093/ije/9.3.227

I expect the author is aware of that: where do you think he got the graph from if there's only 'gated copies'? But Sci-Hub links are unstable even if you don't mind linking them.