三国遺事
"Hyangga" was the first uniquely Korean form of poetry. It originally indicated songs that were sung in the Silla period. Only twenty five survive. The "Samguk Yusa" contains 14 poems and the "Gyunyeojeon", a set of biographies of prominent monks, contains eleven poems. Both these classic works were written much after the Unified Silla, in the subsequent Goryeo dynasty, yet the poems in the Samguk Yusa appear to be based on no-longer-extant records actually from the Silla period.