This documentation includes Louis Siret's notes on his own library and other publications of interest, as well as the catalogue entries and inventories drawn up by staff at the National Archaeological Museum while organising Louis Siret's library, acquired along with his archive by ministerial order on 8 August 1956.
The notes and drawings made by Louis Siret are summaries of the books, journals and articles he read on a wide variety of topics, all related to his fields of interest. He added commentaries to these notes, contrasting his ideas with those of the authors he read. Additionally, the Belgian archaeologist kept a notebook with the word "Bibliotheque" written on the cover, in which he wrote down the titles of the books in his collection, first indexing them by subject and then, within each subject category, listing the author's name, book title and a series of numbers.
Another set of documents in this group is the catalogue entries of Louis Siret's library, which may have been made in the 1930s when the archaeological collection was packed up or, more probably, in the 1950s-60s, after the books, periodicals and pamphlets in his library were acquired along with his archive by ministerial order on 31 August 1956.
The entries have been preserved in their original envelopes, with writing on the back indicating the number of the box in which the corresponding books were packed, the number of paper slips inside the envelope, and notes on whether any of the publications were already in the library of the National Archaeological Museum. These duplicates are indicated with a red mark on the slip of each work already owned by the MAN.