"The Problem of Speech Genres,"Bakhtin (1986) provided his most thorough exploration of issuesrelated to the stability as well as questions related to the trans-formativity or instability of genres. Bakhtin's concept of genre wasintricately linked to his dialogic understanding of language and hisrefusal to accept the Saussurean division between langue and paroleand the consequent attempt to create a rule-governed science oflanguage.
The full pdf of Bakhtin's writting - "The Problem of Speech Genres"(https://livelongday.files.wordpress.com/2011/08/bakhtinspeechgenres.pdf)