El libro de los cuentos perdidos
He called his collection of nascent stories "The Book of Lost Tales". This became the name for the first two volumes of "The History of Middle-earth", which include these early texts. Tolkien never completed "The Book of Lost Tales"; he left it to compose the poems "The Lay of Leithian" (in 1925) and "The Lay of the Children of Húrin" (possibly as early as 1918).