Supplement to the fourth, fifth, and sixth editions of the Encyclopaedia Britannica, 全6巻本のダウンロード先(archive.org)のURLの案内としては下記が有用である。
The Online Books Page: Supplement to the Fourth, Fifth, and Sixth Editions of the Encyclopaedia Britannica; With Preliminary Dissertations on the History of the Sciences
https://onlinebooks.library.upenn.edu/webbin/book/lookupid?key=olbp79813
https://onlinebooks.library.upenn.edu/webbin/book/lookupid?key=olbp79813
Supplement to the fourth, fifth, and sixth editions of the Encyclopaedia Britannicanについては、下記の紹介が有用である。
“Supplement to the fourth, fifth, and sixth editions”,britannica.com > Home > Lifestyles & Social Issues > Education
https://www.britannica.com/topic/Encyclopaedia-Britannica-English-language-reference-work/Supplement-to-the-fourth-fifth-and-sixth-editions
https://www.britannica.com/topic/Encyclopaedia-Britannica-English-language-reference-work/Supplement-to-the-fourth-fifth-and-sixth-editions