E invoice on non gst items.

As e invoice is not applicable for the exempt and nil rated goods in FAQ issued by CBIC.

Is there any other reference of section or rules or notification where it is clearly mentioned that exempt/nill rated/non gst/b2c supplies are out of the ambit of e invoice.

need to give reference in a reply and found this only in FAQs. So pls guide is there any other reference available.