Acrobatics:
Thief (book) - Bravil - In S'krivva's house - upstairs on a bookself.
A Dance in Fire, v1 - Cheydinhal In Ganredhel's House in the dresser
A Dance in Fire, v4 - Kvatch In Castle Kvatch, Great Hall on the hall table
The Black Arrow, v 1 - The Brindle Home in Torbal the Sufficient's house, chest at foot of bed
Mystery of Talara, v 1 - Two Sides of the Coin
Alchemy:
Song of the Alchemists - The Imperial City's Arcane University in the Lustratorium
A Game at Dinner - In the Chorrol Mages Guild in the small room next to Angalmo the alchemist.
Mannimarco, King of Worms - found in a display case in the Mystic Archives in the Arcane University
De Rerum Dirennis - Skingrad: All Things Alchemical, 2nd floor shelf
Calcinator Treatise - Can be obtained as a reward from the quest Two Sides of the Coin
Alteration:
Daughter of the Niben - Third floor of Skingrad Mages Guild on a bookshelf
The Dragon Break - Shelf in a table on second floor of Dovyn Aren's house in Imperial City Elven Gardens.
Reality & Other Falsehoods - Shelf on second floor of Southern Books in Leyawiin
The Lunar Lorkhan - Two Sides of the Coin
Sithis (book) - In the bookshelves in the study room of Deepscorn Bastion.
Armorer:
The Armorer's Challenge - Imperial City Market District, First Edition
Last Scabbard of Akrash - Imperial City At the A Fighting Chance in the Market District
Light Armor Repair - Bravil Inside Castle Bravil, on a shelf at the barracks.
Cherim's Heart of Anequina - Imperial City Market District in the First Edition bookstore
Heavy Armor Repair - Looted randomly from Marauder chests and tombs
Athletics:
The Ransom of Zarek - Imperial City Arena Bloodworks, inside a cupboard
A Dance in Fire, v3 - Skingrad Inside Uuras the Shepherd's House, in a bookshelf on the top floor
The Red Kitchen Reader - Anvil in Castle Anvil, desk in Baeralorn's bedroom in private quarters
Beggar - Cloud Ruler Temple, Great Hall, on a shelf in the North East corner of the room.
The Argonian Account, Book 1 - Given as a random quest reward
Blade:
Words and Philosophy - Chorrol Inside Modryn Oreyn's House on a shelf
2920, Morning Star (v1) - In Castle Leyawiin in the Steward and Healer's Private Quarters
Song of Hrormir - In the Imperial City Arena Branwen and Saliith's Chest
Fire and Darkness - Found as random loot
Battle of Sancre Tor - Bravil: Castle Bravil Behind the throne in a locked display case (Very Hard lock).
Block:
The Warp in the West - Cloud Ruler Temple, Great Hall, on a table and randomly looted
Death Blow of Abernanit - Anvil Fighters Guild, in a chest atop dresser in a locked second floor bedroom off dining hall.
The Mirror - Leyawiin In the City Watch Barracks, in a shelf in the storage room on the ground floor
A Dance in Fire, v2 - Imperial City At the Elven Gardens District in a guard house
Warrior - In Castle Leyawiin in the Lords' Manor Private Quarters in the Countess's bed chamber
Blunt:
Night Falls on Sentinel - In Goblin Jim's Cave, shelf on top level
Mace Etiquette - Randomly looted
The Legendary Sancre Tor - Chorrol On the third floor of Vilena Donton's house, located on a shelf near the balcony door.
The Importance of Where - Bravil In Castle Bravil, on a table in the first room of the dungeon
King - Anvil In Castle Anvil, on a shelf in the royal quarters
Conjuration:
Mythic Dawn Commentaries 1 - The Path of Dawn quest
The Doors of Oblivion - Anvil Mages Guild library
Liminal Bridges - Imperial City, Arcane University Mystic Archives
2920, Hearth Fire (v9) - Bruma's Great Chapel of Talos on a shelf in the Chapel Hall
2920, Frostfall (v10) - Anvil's Chapel of Dibella, in a room at the eastern side of Chapel Hall
The Warrior's Charge - Jorundr's chest in Two Sides of the Coin quest; found in boss level necromancer and conjurer loot
Destruction:
The Horrors of Castle Xyr - Third floor of Bravil Mages Guild on a bookshelf
Response to Bero's Speech - The Imperial City's Arcane University in the Mystic Archives
Mythic Dawn Commentaries 2 - Third floor of West Weald Inn in Skingrad
A Hypothetical Treachery - Skingrad in Skingrad Castle, on shelf in bedroom of Lord's Manor
The Art of War Magic - Leafrot Cave on a shelf in a room just after entrance around the alchemy equipment
Mystery of Talara, v 3 - Jorundr's chest in Two Sides of the Coin quest; found in boss level necromancer and conjurer loot
Hand to Hand:
Immortal Blood - Bandit Camp near Vilverin
Master Zoaraym's Tale - Jalbert's Roam in Vilverin
Ahzirr Trajijazaeri - Dark Brotherhood Training Room in Cheydinhal
The Wolf Queen, v 2 - Skingrad In Skingrad Castle, on a tall bookshelf in Hassildor's room in the Lord's Manor
Way of the Exposed Palm - Fieldhouse Cave in the Black Balconies of Fieldhouse in the south-westernnmost little enclave under a huge Cairn Bolete mushroom
Heavy Armor:
Hallgerd's Tale - Chorrol At the Fighters Guild, in a chest on the top level of the tower
2920, MidYear (v6) - Chorrol in Fire and Steel, on shelf
Chimarvamidium - Imperial City In the Imperial Legion Compound, inside a shelf at the barracks of the Imperial Legion Offices
How Orsinium Passed to Orcs - Bruma At Castle Bruma, on a desk at the center of the Lord's Manor
History of the Fighters Guild - Fort Homestead, outside the Imperial City. Found inside a chest in the dungeon's last room. (This appears to be a random skillbook; you may also find another title in this chest rather than the History of the Fighters Guild.)
Fighters Guild History, 1st Ed. - Ground floor of the Mystic Archives in the Arcane University
Illusion:
Mythic Dawn Commentaries 3 - Purchase in First Edition in Imperial City Market District
The Wolf Queen, v 3 - In the downstairs part of the Bruma Mages Guild
The Argonian Account, Book 3 - Mystic Archives of the Arcane University
Incident in Necrom - Dresser on second floor of Willow Bank in Cheydinhal
Palla, volume 1 - Table in final level in Arkved's Tower (south of Lake Poppad)
Mystery of Talara, v 4 - Jorundr's chest in Two Sides of the Coin quest; found in boss level necromancer and conjurer loot; under a table in tower above Fort Caractacus.
Light Armor:
The Refugees - Imperial City Market District First Edition bookstore On a bookself
Lord Jornibret's Last Dance - In Bleak Flats Cave, on a wooden table in the southern area of the cave. (Near Erthor during the Skingrad Recommendation Mages Guild quest)
The Rear Guard - Cheydinhal in Dark Brotherhood Sanctuary, in chest in training room
Ice and Chitin - Leyawiin Inside Ahdarji's House, in a chest at the foot of the bed on the second floor of the west wing.
Rislav The Righteous - Randomly looted from bandits and vampires
Marksman:
A Dance in Fire, v5 - Regner's House in Bruma Sitting atop a small table in the downstairs bedroom area.
The Gold Ribbon of Merit - Cheydinhal in Dark Brotherhood Sanctuary, in chest in training room
Vernaccus and Bourlor - Chorrol in Renoit's Books, on bookshelf on ground floor.
Father Of The Niben - Bravil Castle Private Quarters, North Wing.
The Black Arrow, v 2 - Found in Teinaava's chest inside the Dark Brotherhood living quarters.
Mercantile:
A Dance in Fire, v6 - Chorrol in Casta Scriobonia's house, on shelf on 2nd floor
A Dance in Fire, v7 Can be found as part of the quest Two Sides of the Coin
The Wolf Queen, v 4 - Imperial City At the Market District, in the Office of Imperial Commerce, on the counter
The Buying Game - Imperial City Elven Gardens District in Fathis Ules's house
2920, Sun's Height (v7) - Found in the Black Horse Courier building, in the Imperial City Market District, on top of a desk in the back corner.
Mysticism:
Before the Ages of Man - Imperial City: Arcane University - Chironasium - sitting on an Altar of Enchanting, on the southwest wall
The Black Arts On Trial - Imperial City Market District Sold at the Mystic Emporium.
Mythic Dawn Commentaries 4 - Picked up in the sewers after fighting Raven Camoran and his Mythic Dawn Guards
The Firsthold Revolt - Cheydinhal The Mages Guild basement.
2920, Sun's Dawn (v2) - Skingrad's Great Chapel of Julianos On a desk downstairs in Chapel Hall, in a small room to the north from where you just entered the area.
Souls, Black and White - Echo Cave in a chest where you defeated Mannimarco in the Confront the King mage guild quest.
Restoration:
Withershins - Library in Leyawiin Mages Guild
Notes on Racial Phylogeny - A chest in the Chapel Hall of Chorrol's Chapel of Stendarr
The Exodus - Shelf in the chapel hall of Skingrad's Great Chapel of Julianos
2920, Rain's Hand (v4) - Bravil's Great Chapel of Mara On a shelf in the Chapel Hall
Mystery of Talara, v 2 - Jorundr's chest in Two Sides of the Coin quest; found in boss level necromancer and conjurer loot
Security:
The Locked Room - Anvil: Smuggler's Cave
The Wolf Queen, v 1 - Bravil Inside Dro'shanji's House, on a shelf
Proper Lock Design - Imperial City Waterfront in Dareloth's house, on desk on 2nd floor (complete the Thieves Guild quest line for access)
Advances in Lock Picking - Cheydinhal In Mach-Na's Books and the Fingerbowl Cave, at the top level on a slab of rock
Surfeit of Thieves - Northwest of Leyawiin, Telepe
Sneak:
Sacred Witness - Loot on the Dagon Shrine quest, in the Lake Arrius Caverns, specifically in the Shrine Living Quarters.
The Wolf Queen, v 6 - Cheydinhal At the Dark Brotherhood Sanctuary, on a bookshelf in the large entrance lobby with a table and two chairs nearby.
2920, Last Seed (v8) - Bravil Inside City Swimmer's House, on a dresser
Legend of Krately House - Cloud Ruler Temple In the library, on the first bookshelf near the stairs
Purloined Shadows - Randomly looted
Speechcraft:
Biography of the Wolf Queen - Reward from the quest Caught in the Hunt and in Imperial City Waterfront in Armand Christophe's house, in chest
The Wolf Queen, v 5 - Imperial City Temple District in Hastrel Ottus's house, on a table at the ground floor
2920, Second Seed (v5) - Imperial City Palace In Chancellor Ocato's quarters, on a bookshelf
The Wolf Queen, v 7 - Cheydinhal In the Castle, on a bookshelf at the lord's quarters