A very rich and clarifying article by Nate Straight in which he discusses the definition of traditional card games. He really nailed the concept and his definition is fundamental to further understand the concept of modern traditional card games.
EndersGame's Articles About Playing Cards
EndersGame is one of the most influentional BGG users, widely known for his immense contribution to the site through reviews and articles. He's also a traditional card game enthusiast and has a lot of articles written on this topic.
The Complete Book of Solitaire and Patience Games
This is the most comprehensive book on this topic I found so far, it's the bible of traditional solitaire. It contains over 200 games, for one and two decks, including all the classic games, its variations, plus new ones created by the authors. It was originally published in 1949, written by Morehead and Mott-Smith, two autorithies on the subject.