“Dar le” is in traditional Irish used in the sense “according to [a person]”, “as it seems to [a person]”. However, among learners you do see stuff like “dar leis na staitisticí”, as though statistics was a person, or maybe a thinking and moving machine. However, AI has not yet developed that far, so we shall say de réir na staitisticí. De réir followed by a genitive form is what you use for “according to [a written source of information]”. Dar le is used what you use for “according to [the information coming from a human source of information or opinion]”. Of course, we can use dar le to refer to dead authors, who still constitute distinct persons: dar le Máirtín Ó Cadhain, but de réir when we are referring to their works: de réir “An Ghaeilge Bheo – Destined to Pass”.
Of course, if aliens descend on Earth, we will even use dar le to refer to their personally given information or opinions: Dar le Zgmbogfzar Ombalo, is féidir taisteal idir-réaltach a dhéanamh, agus is léir go bhfuil taithí aige air “According to Zgmbogfzar Ombalo, interstellar travel is possible, and it is obvious that he has experienced it”. Zgmbogfzar, or just Old Zgmbie to his (her? their?) friends, certainly is able to communicate personally and thus merits the use of dar le.