A modern library would have not only books but audio/video tapes, magazines, journals, etc.
Of course I could use a non-library-specific term like resource or even just item (maybe prepending each with the word library), but I'm wondering if there's a library industry piece of terminology for the individual 'things' being cataloged?
Item is consistently used by the USA's Library of Congress. Consider
Today's Library of Congress is an unparalleled world resource. The collection of more than 164 million items includes more than 38.6 million cataloged books and other print materials in 470 languages; more than 70 million manuscripts; the largest rare book collection in North America; and the world's largest collection of legal materials, films, maps, sheet music and sound recordings.
[...]
Year 2016 at a Glance
Circulated more than 997,000 items for use inside and outside the Library
Preserved more than 10.5 million items from the Library's collections
Recorded a total of 164,403,119 items in the collections:
24,189,688 cataloged books in the Library of Congress classification system
14,660,079 items in the nonclassified print collections, including books in large type and raised characters, incunabula (books printed before 1501), monographs and serials, bound newspapers, pamphlets, technical reports, and other printed material
125,553,352 items in the nonclassified (special) collections, including:
3,670,573 audio materials, (discs, tapes, talking books, other recorded formats)
70,685,319 manuscripts 5,581,756 maps
17,153,167 microforms
1,809,351 moving images
8,189,340 items of sheet music
15,071,355 visual materials including:
14,290,385 photographs
107,825 posters
673,145 prints and drawings
3,392,491 other items, (including machine-readable items)
Consider the term title.
title noun 1.2 A book, magazine, or newspaper considered as a publication. ‘Two Fox Movietone News clips of the cast and crew arriving and working in Japan and trailers for House of Bamboo and the rest of the recent spate of Fox film noir titles fill out this DVD.’ - ODO
As the example in the definition shows, titles are not restricted to paper publications.
However, although actual libraries allow searches for titles, they tend to use the generic term item to refer to the resources, as the following example shows.
The Cairns library uses the generic term item (emphasis, mine).
03 - Library Guide - How To - Reserve An Item
You can reserve up to fifteen (15) items that are out on loan or at another library by using our catalogue either in the library or at home.
These items aren't restricted to books. The catalog search boasts of "over 160,000 items made up of the following:"
I would suggest published work or publication; with preference leaning toward "published work" or even just "work"
Example Sentence: The library holds over 10,000 published works.
Example Sentence: The library has the complete works of Ray Bradbury.
A thing or things done or made; the result of an action.
3.1 A literary or musical composition or other piece of art.
3.2 The artistic production of a particular author, composer, or artist, regarded collectively.
The preparation and issuing of a book, journal, or piece of music for public sale.
1.1 The action of making something generally known.
1.2 A book or journal issued for public sale.
