The EJLPP has two essential parts: first, a census of books once owned by Jesuit institutions which are currently available in libraries, and second, the use of library inventories from the 16th, 17th, and 18th centuries from Jesuit institutions. The inventories I have used to date are:
Rijksarchief Antwerpen, Archief Nederduitse Jezuïetenprovincie (Flandro Belgica) 3278: Bibliotheekcatalogus. S.d. This is probably the one Fabri & Lombaerd called incomplete from 1730. (I only have a portion of this one.)
Rijksarchief Antwerpen, Archief Nederduitse Jezuïetenprovincie (Flandro Belgica) 2045 Stukken betreffende een proces voor de Geheime Raad tussen Joachim Trognesius, boekdrukker in Antwerpen, aanlegger, en de provincie, verweerder, over het drukken van boeken voor de Sociëteit. 1613. 1613 1 pak Vlaams-Belgische Provincie van de Jezuïeten, 1542-1773
Rijksarchief Antwerpen, Archief Nederduitse Jezuïetenprovincie (Flandro Belgica) 2046: Catalogus van de boeken over architectuur, achtergelaten door P. Guilielmus Cornelii, overleden te Leuven in 1660. [17de eeuw]. 1601-1700 1 stuk
Rikjsarchief Leuven, Jezuïeten College Leuven. 20. Catalogus van de schenkingen aan de bibliotheek, 1635.
Archivio Arcivescovile di Bologna 244, Libreria, Missioni, Patronati
Archivio Comunale di Ferrara, Ex Patrimonio Gesuitico 78: Descriptio Biblioteca Excollegi Societatis Iesu Balneocaballi Consignat’ Ill.me Comunitati Balneo Balneocaballi (Bagno Cavallo)
Archivio di Stato di Firenze, Compagnie Religiose Soppresse da Pietro Leopoldo. Gesuiti di Livorno. Inventario dei Libri, Fogli, Documenti, attenenti all’Istoria, Diritti, Ragioni, ed Azienda del gia` Collegio della Compagnia di Gesu di Livorno Collegio e sua fondazioe 1708 26 m.zo.... Inventari, e consegne di Mobili e Arredi del Collegio di Livorno 1773-1775
Archivio di Stato di Firenze Comp Rel Soppresse dal Pietro Leopoldo 999, Filza 3, n. 104: COLLEGIO S. GIOVANNI EVANGELISTA, FLORENCE. Inventario di tutti i beni mobili di Casa fatto a 1.o di X.bre di 1578 per ordine di’l P. Sebastiano Morales Visitatore della Provincia della Toscana
Archivum Romanum Societatis Iesu Rom 124 I, ff. 235r-236v: Catalogo de libri Theologi del Collegio di Siena 1565
Archivum Romanum Societatis Iesu Rom 121, ff. 148r-150v: Inventario delli libri del Collegio de Fiorenza fatto a bj 15 di Febraro 1566 [i.e. 1565]
The inventories consist of lists--sometimes full titles, sometimes portions of titles, sometimes a combination of part of an author's name and a title, and sometimes just author names. Few of them have been printed in whole or in part. You can find a detailed description of the inventories of Florence (1565 and 1578) and of Siena (1578) in the appendix of my Jesuit Foundations and Medici Power. Among these ten inventories, the combined total of individual titles is 3,452. This includes several repeats.
Occasionally, an inventory will include other information; for example, the price paid for a book, the donor of the book, how many volumes in a given text, etc. For the most part, though, they provide very few clues. This suggests that they were meant as temporary records, which is to say that they were not intended to be an official catalogue of the library collection, but instead to serve as a portion of the inventory of the whole property. The later book lists (particularly the eighteenth-century ones) are more detailed. These were created at the time of the suppression of the Jesuits, and therefore needed to be done more carefully. The books were to be sold or transferred to other institutions, and those writing down titles and authors clearly took greater care than their earlier counterparts. In the 16th and 17th century, inventories were part of the continuing work of an institution. In the 1760s and 1770s, as the institutions were transformed or shuttered, those in charge of transferring the material wealth of those institutions had different responsibilities. For example, a different religious order might wish to request some books, but they would need to know which books were available. The government might instead decide to auction all the possessions of a given house or college, at which point they would need to evaluate the worth of said possessions.