It is my great pleasure to announce the guest blog on the British Library website by our colleague, Lina Elhage-Mensching, on the Bohairic–Arabic Holy Week lectionary Add MS 5997 dated 1273 CE. This showcase is one of the results of a collaboration between the British Library and the Coptic Old Testament Project at the Göttingen Academy of Sciences and Humanities in Lower Saxony. Lina analyses this lectionary in the framework of the DFG project Digital Edition of the Coptic Holy Week Lectionary (n° 491266891).