Bibliography (7):

1. https://patents.google.com/?inventor=Johan+Bjorksten&before=priority:19950701&after=priority:19000101&sort=old

2. Hectograph Printing, Duplication, Copying

3. ​ ‘Johan Bjorksten (aging)’ directory

4. Wikipedia Bibliography:

   1. Lipofuscin

   2. Trypsin  :

      https://en.wikipedia.org/wiki/Trypsin

   3. Bacillus cereus  :

      https://en.wikipedia.org/wiki/Bacillus_cereus

   4. Mike Darwin