It probably was, difficult to tell as it is extremely clean HTML, but the referencing seems to hint at bibtex (a referencing system for latex), with class names

It probably was, difficult to tell as it is extremely clean HTML, but the referencing seems to hint at bibtex (a referencing system for latex), with class names like "bibitem" and "biblabel". >and if so how How is easy, they are many different programs, here are a few: https://enc.com.au/docs/latexhtml/ https://enc.com.au/docs/latexhtml/. Which in particular is a bit harder, there is no <meta name="generator" content="... that some Latex->HTML converter leaves in, but I suspect you could turn that feature off. I think this page uses custom CSS too, as its using Google Fonts.