Save object in ScriptableObject

I want to save a list of "ClassA" with different typs in the Class "DatabaseA".
Currently i cant save a System.object in my list. All other types work.

public class ExampleClass

{

  int i;

  System.object obj, <-- will not be saved in the ".asset" file

  float f;

}



public class DatabaseA: ScriptableObject

{

    public List<ExampleClass> ListExampleClass;

}

 

Thx for your Answer. Yehr convert the type to a string is good idea.
float, int, and so on... can be easly converted from string.
But how i can convert a string to GameObject/Prefab, Texture2D, AudioClip?
Unity also converts it from a string to a reference.

Hint: I want to edit the stored data in a EditorWindow.

Instead using the System.Object it would fit my needs using UnityEngine.Object if it is possible convert a UnityEngine.Object to base Types like uint, int, float and bool.