Some people claim the rules pertaining to the Constitution’s “Convention for Proposing Amendments” are largely unknown, but there actually is quite a lot of law on the subject.
Earlier this year, I pulled together that body of law in a legal treatise entitled “State Initiation of Constitutional Amendments: A Guide for Lawyers and Legislative Drafters.” This is actually the latest of several legal treatises I’ve written on various subjects for national publishers, mostly on constitutional and property law.
Section 3.9 of the treatise deals with the rules by which Congress must call the convention. That section has now been updated and supplemented extensively. You can read the treatise here. It is primarily designed for legal professionals, but many lay people will find it useful.