Look for the peg holes, paper/cel size, and see if you can determine the paper used (some have water marks). Second, you want to check for markings near the peg holes.
These identify the item as to what show, episode, or other use for the item. The number in the corner is used for its sequence in the scene. These drawings and cels sole purpose was to be used to create the cartoon, not to be kept as art. I believe these items to be authentic, but I do not create certificates at this time.
I hope this helps in your decision in purchasing from me. This item is in the category "Collectibles\Animation Art & Merchandise\Animation Art".The seller is "joiousanimation" and is located in this country: US. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech Republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, Korea, South, Indonesia, Taiwan, South Africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi Arabia, United Arab Emirates, Qatar, Kuwait, Bahrain, Croatia, Republic of, Malaysia, Chile, Colombia, Costa Rica, Panama, Trinidad and Tobago, Guatemala, Honduras, Jamaica, Antigua and Barbuda, Aruba, Belize, Dominica, Grenada, Saint Kitts-Nevis, Saint Lucia, Montserrat, Turks and Caicos Islands, Barbados, Bangladesh, Bermuda, Brunei Darussalam, Bolivia, Egypt, French Guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman Islands, Liechtenstein, Sri Lanka, Luxembourg, Monaco, Macau, Martinique, Maldives, Nicaragua, Oman, Pakistan, Paraguay, Reunion, Uruguay.