Famed naturalist Charles Darwin amassed an impressive personal library over the course of his life, much of which was preserved and cataloged upon his death in 1882. But many other items were lost, including more ephemeral items like unbound volumes, pamphlets, journals, clippings, and so forth, often only vaguely referenced in Darwin’s own records.

For the last 18 years, the Darwin Online project has painstakingly scoured all manner of archival records to reassemble a complete catalog of Darwin’s personal library virtually. The project released its complete 300-page online catalog—consisting of 7,400 titles across 13,000 volumes, with links to electronic copies of the works—to mark Darwin’s 215th birthday on February 12.