Retrieves and normalizes scholarly article metadata and abstracts from the 'Crossref' REST API < https://www.crossref.org/documentation/retrieve-metadata/rest-api/>, the 'OpenAlex' API < https://help.openalex.org/> and the 'Scopus' Search API < https://dev.elsevier.com/sc_apis.html>. Provides bibliographic searches, cursor pagination, publication date and author filtering, abstract retrieval by Digital Object Identifier (DOI), cached batch enrichment, merging of duplicate records, metadata-quality audits, reproducible search snapshots, local archives with integrity verification, and export to comma-separated values (CSV), 'BibTeX' and 'RIS' citation files. Network requests support configurable timeouts and test callbacks. 'Scopus' searches require an 'Elsevier' API key; 'Crossref' queries do not. 'OpenAlex' supports limited keyless searches and authenticated pagination.