Which famous children's book features the line "I think I can"?

The Little Engine That Could is an American folktale (existing in the form of several illustrated children's books and films) that became widely known in the United States after publication in 1930 by Platt & Munk. The underlying theme is the same—a stranded train is unable to find an engine willing to take it on over difficult terrain to its destination. Only the little engine is willing to try and, while repeating the mantra "I think I can, I think I can", overcomes a seemingly impossible task.

Source: Wikipedia