This achievement isn't as hard as it looks,But it's not easiest achivment obtainable but still.
If you need a more sticky guide use The Well Read Achievement | World of Warcraft Pro for both Horde and alliance.
This guide show the cordinates of all the books.
*Aegwynn and the Dragon Hunt - 61.52 Tirisfall Glades
*Aftermath of the Second War - Scarlet Monastery, Secret passage where High Inquisitor is located.
*Arathor and the Troll Wars - 62.20 Hillsbrad Foothills, outside the church in Tarren Mill or within Scarlet Monastary
*Archimonde's Return and the Flight to Kalimdor - 62.38 Barrens, in Ratchet or within Scarlet Monastery
*Beyond the Dark Portal - 26.77 Stranglethorn Vale, in Booty Bay or within Scarlet Monastery
*Charge of the Dragonflights - 62.36 Barrens, in Ratchet or 34.39 Ashenvale
*Civil War in the Plaguelands - 67.37 Undercity, Stratholme and Scarlet Monastery
*Empires' Fall - Booty Bay Inn and Gadgetzan Inn
*Exile of the High Elves - Only found within Scholomance
*Icecrown and the Frozen Throne - 43.65 Elwynn Forest, Goldshire Inn, Scarlet Monastery, Scholomance and Stratholme
*Ironforge - the Awakening of the Dwarves - 37.77 Tanaris, 35.49 Loch Modan and Black Rock Depths
*Kel'Thuzad and the Forming of the Scourge - Southshore Inn, Scarlet Monastery, Scholomance and Stratholme
*Kil'jaeden and the Shadow Pact - Within Scholomance and Stratholme
*Lethargy of the Orcs - 61.55 Barrens, in Gadgetzan and 85.69 Elwynn Forest
*Mount Hyjal and Illidan's Gift - 61.39 Barrens, in Gadgetzan
*Old Hatreds - The Colonization of Kalimdor - 51.29 Tanaris and within Scholomance
*Rise of the Blood Elves - Only found within Scholomance
*Rise of the Horde - 59.58 Durotar, within Tirigarde Keep
*Sargeras and the Betrayal - 61.39 Barrens, in Ratchet
*Sunwell - The Fall of Quel'Thalas - 27.77 Stranglethorn Vale, in Booty Bay
*The Alliance of Lordaeron - 47.52 Dun Morogh, in Kharanos and 63.20 Hillsbrad Foothills, in Tarren Mill
*The Battle of Grim Batol - 83.13 Stormwind City, and 10.60 Wetlands
*The Betrayer Ascendant - 66.76 Darnassus City
*The Birth of the Lich King - Only found within Scholomance and Stratholme
*The Dark Portal and the Fall of Stormwind - 26.44 Redridge Mountains, 82.15 Stormwind City, 47.54 Swamp of Sorrows
*The Founding of Quel'Thalas - Only found withing Scholomance
*The Guardians of Tirisfal - 72.9 Stormwind City
*The Invasion of Draenor - Only found within Scholomance
*The Kaldorei and the Well of Eternity - 71.7 Stormwind City and 10.60 Wetlands
*The Last Guardian - 37.47 Loch Modan and 52.53 Westfall
*The Lich King Triumphant - Only found within Scholomance and Stratholme
*The New Horde - 61.54 Barrens
*The Old Gods and the Ordering of Azeroth - Only found within Black Rock Depths and Scholomance
*The Scourge of Lordaeron - 34.49 Ashenvale, 27.77 Stranglethorn Vale, also within Scarlet Monastery, Scholomance, and Stratholme
*The Sentinels and the Long Vigil - 27.77 Stranglethorn Vale
*The Seven Kingdoms - Only found within Scholomance and Stratholme
*The Twin Empires - 27.77 Stranglethorn Vale and 52.27 Tanaris
*The War of the Ancients - 49.16 Darnassus City and 21.61 Stormwind City
*The World Tree and the Emerald Dream - Only found within Scarlet Monastery
*War of the Spider - Only found in Scarlet Monastery, Scholomance and Stratholme
*War of the Three Hammers - Lakeshire Town Hall, Dwarven District in Stormwind City, Black Rock Depths, and Scarlet Monastery
*Wrath of Soulflayer - 27.77 Stranglethorn Vale and 52.27 Tanaris
Added some pics on SM Libraryand Scholomance books