Finding the source of a sutta How do you find out the source of a sutta? For example, MN 109, SN 56.11 
begin


  I have heard that on one occasion the Blessed One


How do we know who this author is? Is there general guidance on who to attribute the suttas to?
I don't know much about this but according to Wikipedia (here and here) it was Ananda who narrated the stories in the suttas.


  A council of 500 Arahats was held at Rajgir (Sanskrit: Rājagaha) to agree the contents of the Dhamma and Vinaya. Ananda recited the Suttas, such that each begins: ‘Thus have I heard’.