found: Work cat: Kato, T. Young children's ways of playing "Concentration" (a card game), 2010:p. 6 (Concentration is another card game young children enjoy playing; they find two identical cards; requires the ability to think and make mental relationships to make pairs; requires the ability to remember where a card is and the ability to think logically)
found: Grandparents.com, Feb. 28, 2017Home > Grandkids > Activities, Games & Crafts (How to play Concentration - Card game. Also known as Memory or Pairs)
found: Classic games and puzzles WWW home page, Feb. 28, 2017:card games (Concentration -- The game where a good memory, observation skills, and a little luck will be the keys to your success. This game is also known as Memory and Pelmanism)