[Activities & Places] How to save and display the criterias again when hitting the back button ?

Hi,
We are using Activities and Places.
I have a search view with several fields (criterias) and a submit button. When the user selects a few criterias and clicks
on the submit button, the activity runs the search method and displays the results in a new result view.
If the user goes back the search view is displayed again but the previous selected criterias are lost.
How can i save them ?
I know it has something to do with places and tokens and the history class but i have not found a clear example yet.
Can someone give me some explanation or point me to a link ?

Thanks for helping.

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