> I loved his articles in the ACM.

This is a super minor correction on my part, but this is a weird phrasing because "the ACM" is a huge organization that publishes proceedings for a great range of interests --- it isn't a venue in itself. The name of the venue you're looking to reference is Communications of the ACM, more commonly just referred to as Communications or CACM.

As an aside, Communications is a sort of unique venue for publication. The submissions are peer-reviewed, but the nature of the submissions is more similar to a blog post or editorial article than traditional papers you'll find in other proceedings from conferences and journals (and, indeed, the ACM refers to CACM as a "magazine"). It makes for good "fun" reading!