Hi Mary, The Krohn's are a very big family, so you will need your "great grandmother's name" because likely your grandma's name may not appear. Most of the records are of the older generation. Provide as much info as you have on your great grandparents. If your grandmother is still living she can tell you those names.
If your Grandma is not living, perhaps her birth certificate would help you to find out about her parents names. I am sure if you have the great grandparents names someone on this forum will have the answers!
Please give more information if you have any!If not try to look up your Grandmother's records that would give you some clue.Good luck!