have made a start to show willing there are many more references but mostly in the academic literature inaccessible to general users of the i'll use these where needed but will try and find some references that can be accessed freely as well i have to declare a potential coi here i am a practitioner of cat so i have a vested interest in the article however i guess it also means i have ready access to the sources needed so maybe i'm not in a bad position to do this as long as others can check the neutrality of what i contribute talk