Creating 3d Animation by Nick Park:
• History of claymation
• Complete process involved

Various Short Animations:
• A Perfect Date by Girija Likhite -
  www.dsource.in/case-study/perfect-date/index.html

• The Gift by Himali Vadalia (one of my senior)
  The big snit, www.youtube.com/watch?v=90SIuISIVB8

About old age:
• www.britannica.com/EBchecked/topic/426737/old-age

For all sort of queries related to claymation:
• www.animateclay.com

Experience of various clay animators:
• www.tasionline.org/tag/clay-animation/
• www.youtube.com/watch?v=m2HpkP0fytg