if you have any phrase near the ads that can encourage users to click the ads then you should use "Sponsored Links" or "Advertisements" label above the ads to avoid invalid clicks. ref: https://www.google.com/adsense/support/bin/answer.py?hl=en&answer=48182
You can NOT use headings like SPONSORS & ADVERTISEMENT with Adsense, as Google itself shows "Ads by Google" with all their ads. So why do you need to add it anyway!
Come on. You've got to make some small attempt to read Google AdSense rules. You can't make any suggestions whatsoever that encourages the visitor to click on your ads. Putting text that might be deem suggestable is a no-no. Make sure you don't get yourself banned by mistake take a look at AdSense TOS.