Research built from primary material rather than aggregated summaries.
Work begins with the sources themselves. A corpus is assembled and its provenance established before anything is claimed from it; where a figure or a quotation carries weight, it carries a reference back to where it came from.
That discipline comes from scholarly editing, and it transfers. The same standards of citation and verification a critical edition demands apply as readily to a sector study as to a philosophical text. What changes is the corpus, not the method.