Unfortunately you cannot find such a reference because in the real world of etiquette it does not exist. I'm afraid that a salad fork is necessary for the salad portion of the meal; however, you should not have to use one fork and then another since according to the same rules of etiquette in dinner service, the salad is served by itself and removed before the next part of the meal. So salad fork (the smaller fork on the outside of the place setting; always work from the outside -> in) is used for salad and given up (left on the salad plate) when that portion is done.
To this end there is no going back and forth with forks. Just one at a time
I'll be happy to answer any other meal time or other etiquette questions you may have. Feel free to ask for "August" when posting.
Is there anything further you need with regard to this ? If you provide a positive rating we can close the question; however, no matter what I'll be available to give further details as you may need