Simplify the following text for a Grade 9 native English-speaking person.
Original: The St Albans Psalter ( circa 1130 â `` 45 ) is the best known of a number of important Romanesque illuminated manuscripts produced in the Abbey scriptorium .
Simplified: The St Albans Psalter ( ca . 1130 â `` 45 ) is the best known of a number of important Romanesque illuminated manuscripts produced in the Abbey scriptorium .