Does permissory note needs to be typed on a stamp paper ?

Hi all

I loaned 2.5Lakh and 1Lakh respectively from my friends and relative for buying a land.I need the permissory notes as a proof of source of income tax purposes.

Do I need to sign it on a stamp paper?

If yes of what value?Does it need to be notified?

As I said this document is only for  tax authority if need arises.Friends have given me on good faith and does not require any documents.

I got the template of the permissory note as

 
 " I, Sri._____________________ S/o. _________________________
promise to pay Sri.___________________ S/o.________________
_____________ or order, the sum of Rs.______ (Rupees______________only)  
 
Place:
Date:                  Signature. "