Who wrote the parent trap?

"The Parent Trap" was originally a novel titled "Lisa and Lottie" written by German author Erich Kästner in 1949. The story was adapted into a film by Walt Disney, with the most notable versions released in 1961 and 1998. The 1961 film was directed by David Swift, while the 1998 remake was directed by Nancy Meyers. Both adaptations followed the original premise of identical twin sisters who reunite after being separated at birth.