(For a further understanding of the 10th Age beliefs on the soul, see Avaridus and the Soul)
I like to tell wizards exactly what books they recover if books are to be part of a treasure horde. "1,400 gold worth of manuscripts and tomes" (one, two, or three books) is much less appealing than On the Nature of Magic, The Root of Alteration, and The Gold Codex, isn't it? Of course, this brings us to the idea of medieval and classical naming of books, which I tend to intermix in the Tenth Age. The idea of "books" as we understand them today didn't exist prior to the printing press. Every individual manuscript was a unique object. Sometimes, only the best parts were copied by scribes, sometimes they were rearranged to form something more useful to the individual copying them, sometimes they were interlaced with other material, sometimes they were amended if the copyist disagreed with a certain argument... books were unique. Often, then, the names of books in the 10th Age are taken from the first line, from the first heading, from the physical description of the book as a whole, or from the contents in toto.
It is perhaps important to note that in the 10th Age after the brutal Wars of Necromancy (9th Age) that saw so many corpses march down from the north where customs are not to burn bodies but to bury them, that the art of necromancy recieved a black name. Elves, having always despised it and being most affected by the losses of the War, began to hunt down and destroy necromantic books. Human kingdoms mostly began to outlaw the practice (at least, those "sane" places did; necromancy can still be openly practiced in lands like Essad, Soloth, and the Free Cities) resulting in a stoppage to the flow of necromantic knowledge. Now, in the 10th Age, most human wizards ignore this prohibition, which has caused a vast and many-armed trade network of black market books to become prevalent for mages to acquire the means to complete their libraries and do research in any scholastic field they wish.
To that end, here is a little table to let you roll up some necromantic tomes for when your PCs find some book-treasure.
1. Wyburn's Treatise (800gp, details the idea of the "false soul," describes how one may be made of negative energy, foundational necromantic text)
2. Magister Arman's Black Codex (600gp, lists of incantation-fragments)
3. On the Transmigration of Souls (1200pg, contains elements of Wyburn's Treatise and Arman's Black Codex)
4. The Book of the Underworld (450gp, details the movement of souls from the world of the living to the world of the dead)
5. On the Endless Night (300gp, disguised as a history of the Night Age, this book is actually a carefully constructed cipher that, when decoded, speaks of the elements of necromantic anatomy)
6. Codex of Dark Wisdoms (3500gp, a compilation of knowledge from Incantations, Larksong, and The Great Work, the Codex is a thorough guide to raising the dead and creating monstrous beings)
7. Incantations of the Sepulchre (2200gp, claiming to contain the knowledge of the ancient Khewedi priests, the Incantations actually introduces the reader to the various and sundry chants needed to execute moderately powerful necromancies)
8. The Body of Man (200gp, a simple anatomy book)
9. On the Unnatural Order (1000gp, a descriptive journey through the many types of undeath and death, the ways in which their false-souls operate, and the manners in which the magus may control them)
10. Vermelo's Canto (800gp, features many necromantic chants and incantations developed by the Dorlish wizard Vermelo, none of which details raising the dead at all but rather focus on the more base manipulation of life-energy)
11. Larksong Manuscript (1800gp, purporting to find the meaning of natural life in the song of birds, this manuscript is exceptionally hard to follow but does provide detailed, if obscure, insight into the operation of a number of necromantic principles)
12. The Sixfold Song (2000gp, a poem that, when deciphered properly, reveals extremely interesting and dangerous techniques for the transference of life-energy between living beings)
13. The Shell of Man (1500gp, a detailed manual which sketches the weakest portions of the human body, and the gates through which life-energy may be drawn; often disguised as the Shell of Man)
14. The Three Roads of Fear (1900gp, a manuscript that purports to answer all questions of binding and staying when it comes to energy and souls, emphasizing the palpable fear at the moment of death for effective magic)
15. The Banned Index (2900gp, a master list of incantations)
16. Serapis' Great Work (2200gp, a description of the life and works of the Chimeron wizard Serapis Blacktongue, which includes many of his theories)
17. The Book of Unspoken Whispers (1200gp, a manuscript containing lists of unspoken spell elements; somatic and mental components)
18. On Necromancy (600gp, more of a description of necromantic practices, written at great risk by Reynarius di Llun but never publicly attributed to him)
19. Severin's Manual (450gp, a foundational tome on basic necromantic works)
20. The Book of Poisons (5000gp, one of the hideous books of priests of the Necromancer. Contains unique necromantic spells)