The SPR literature, as it stands right now

What this is, precisely. Europe PMC indexes MEDLINE/PubMed, PMC, preprint servers and more, so its coverage of SPR is a superset of PubMed alone — which matters, because a great deal of SPR methodology appears in analytical chemistry and optics journals that MEDLINE indexes incompletely.

What it is not. No index contains every paper ever published, and no keyword query is a perfect classifier for a topic. Rather than claim completeness we have made the query visible — expand the disclosure below the controls to see exactly what is being asked, and tell us what it misses.