Candied fruit from oranges

Hello
Today we will prepare the candied fruits in accordance with a proven recipe.
On the Internet, there are many ways of quick preparation, but I still prefer to cook properly! We will not add salt to remove bitterness and boil every 10 minutes. We will do everything the old way, as our grandmother did.

For the preparation of candied fruits, any citrus fruits match.
I use:

Mandarin skin of two mandarin
Orange peel from one orange
Lemon peel from one lemon
Sugar 500 grams
Preparation of candied fruits takes two days.