https://www.nedcc.org/free-resources/preservation-leaflets/6.-reformatting/6.1-microfilm-and-microfiche https://www.nedcc.org/free-resources/preservation-leafle

https://www.nedcc.org/free-resources/preservation-leaflets/6.-reformatting/6.1-microfilm-and-microfiche https://www.nedcc.org/free-resources/preservation-leaflets/6... "500+ years under proper storage conditions"