The following playlist is kindly uploaded onto IMEEM by Miri Maaka and is by far the most comprehensive playlist available online. It contains the English version of the OST with a bonus track and two versions of the theme song (JYONGRI - Lullaby for You).

Alternative Playlists:
Tamara's alternative English OST playlist
Sora Key's Japanese OST playlist
Lan Hikari's English and Japanese mix with forgotten game-only tracks. Game-only tracks are low quality.