Hi,If you are asking how can you stop the drawings you have from deteriorating further, I'm not sure there is a lot, if anything you can do. As has been mentioned, It's the acid in the paper.
Maybe some museum web sites have restoration and preservation information on them, it may be worth a try
Someone else here may know something I don't, it's not too difficult a task, believe me 
Phil
www.graphite-art.com