SERVICE BOOKS - They are special books containing the hymns or the services of the Orthodox Church. There are eight as follows: Gospel (Evangelion), Book of Epistles (Apostolos), Psalter (Octoechos or paraklitiki), Triodion, Pentecostarion, Twelve Menaia, Horologion, and Service or Liturgy book (Euchologio or Ieratiko).
Service Book or Ieratikon or Litourgikon or Euchologio. (Sl. Sluzhebnik). The liturgical book containing the prayers and ceremonial order of the various church services including the Liturgy.