Question: Days of Future Future is a continuation of the Simpsons episode that originally aired on what date?

Context articles: Holidays of Future Passed
Lisa's Wedding
Bart to the Future
Four Great Women and a Manicure
A Star Is Born Again
Good Night (The Simpsons short)
Days of Future Future
The Simpsons 138th Episode Spectacular
The Princess Guide
Patty and Selma

"Holidays of Future Passed" is the ninth episode of the twenty-third season of the American animated sitcom "The Simpsons".
 It originally aired on the Fox network in the United States on December 11, 2011.
 Most of the episode is set thirty years into the future, when Bart and Lisa take their children with them to Homer and Marge's house over Christmas, while a pregnant Maggie goes into labor.
 Bart has divorced his wife Jenda and is struggling to become a better father for his two boys, while Lisa has trouble connecting with her rebellious teenage daughter Zia.
 "The Simpsons" creator Matt Groening made a minor uncredited cameo appearance as a sports commentator shouting "goal!"
 during a soccer game.
"Lisa's Wedding" is the 19th episode of "The Simpsons"<nowiki>'</nowiki> sixth season.
 It originally aired on the Fox network in the United States on March 19, 1995.
 The plot focuses on Lisa visiting a carnival fortune teller and learning about her future love.
 It was written by Greg Daniels and directed by Jim Reardon.
 Mandy Patinkin guest stars as Hugh Parkfield and Phil Hartman guest stars as Troy McClure.
 The episode won an Emmy Award in 1995 for Outstanding Animated Program, becoming the third episode of "The Simpsons" to win the award.
"Bart to the Future" is the seventeenth episode of the eleventh season of the American animated television sitcom "The Simpsons".
 It originally aired on the Fox network in the United States on March 19, 2000.
 In the episode, after their picnic in the park is cut short due to a mosquito infestation, the Simpsons stop by at an Indian casino.
 There, Bart is prevented from entering because of his age.
 He manages to sneak in but is caught by the guards and sent to the casino manager's office.
 The Native American manager shows Bart a vision of his future as a washed-up, wannabe rock musician living with Ralph Wiggum, while Lisa has become the President of the United States and tries to get the country out of financial trouble.
 "Bart to the Future" was the second episode of "The Simpsons" after "Lisa's Wedding" to be set in the future.
"Four Great Women and a Manicure" is the twentieth episode of the twentieth season of "The Simpsons".
 First broadcast on the Fox network in the United States on May 10, 2009, it was the second Simpsons episode (after "Simpsons Bible Stories") to have four acts instead of the usual three.
 The episode tells four tales of famous women featuring "Simpsons" characters in various roles: Selma as Queen Elizabeth I, Lisa as Snow White, Marge as Lady Macbeth and Maggie as Howard Roark from Ayn Rand's "The Fountainhead".
"A Star Is Born Again" is the 13th episode from "The Simpsons"<nowiki>'</nowiki> fourteenth season.
 It first aired on the Fox network in the United States on March 2, 2003.
 The episode owes much of its plot to "Notting Hill" (1999).
 While that film is about an actress (Julia Roberts) finding happiness with the owner of an independent bookstore, the Simpsons episode features Hollywood movie star Sara Sloane (Marisa Tomei) falling for Ned Flanders after visiting the Leftorium.
"Good Night" (also known as "Good Night Simpsons") is the first of forty-eight Simpsons shorts that appeared on the variety show "The Tracey Ullman Show".
 It originally aired on the Fox network in the United States on April 19, 1987, during the third episode of "The Tracey Ullman Show" and marks the first appearance of the Simpson family — Homer, Marge, Bart, Lisa, and Maggie — on television.
 After three seasons on Tracey Ullman, the shorts would be adapted into the animated show "The Simpsons".
 "Good Night" has since been aired on the show in the episode "The Simpsons 138th Episode Spectacular" (in its entirety), along with several other Ullman shorts, and is one of the few shorts to ever be released on DVD, being included in the Season 1 DVD set.
"Days of Future Future" is the eighteenth episode of the 25th season of the American animated sitcom "The Simpsons", and the 548th episode of the series.
 It first aired on the Fox network in the United States on April 13, 2014.
 It was written by J. Stewart Burns and directed by Bob Anderson.
 The episode is a sequel to "Future-Drama" and a continuation of "Holidays of Future Passed", set 30 years from the present.
 In this futuristic installment, Bart goes to a clinic to rid himself of his feelings for his ex-wife Jenda (who is now dating a xenomorph-like alien named Jerry), Lisa must choose whether or not to cure her zombie husband Milhouse after he gets bitten by a homeless zombie, and Marge (after putting up with years of Homer dying and being cloned back to life by Professor Frink) loads Homer onto a flatscreen monitor and throws him out of the house.
"The Simpsons 138th Episode Spectacular" is the tenth episode of "The Simpsons"<nowiki>'</nowiki> seventh season.
 It originally aired on the Fox network in the United States on December 3, 1995.
 As the title suggests, it is the 138th episode and the third clip show episode of "The Simpsons", after "" and "Another Simpsons Clip Show".
 While the "138th Episode Spectacular" compiles sequences from episodes throughout the entire series like the previous two, it also shows clips from the original Simpsons shorts from "The Tracey Ullman Show" and other previously unaired material.
 Like the Halloween specials, the episode is considered non-canon and falls outside of the show's regular continuity.
"The Princess Guide" is the fifteenth episode of the twenty-sixth season of the American animated sitcom "The Simpsons", and the 567th overall episode of the series.
 It originally aired on the Fox network in the United States on March 1, 2015.
 The episode was dedicated to the memory of Leonard Nimoy, who died two days before the episode aired.
 Nimoy guest-starred in two "Simpsons" episodes, "Marge vs. the Monorail" and "The Springfield Files".
Patty and Selma Bouvier ( ) are fictional characters in the American animated sitcom "The Simpsons".
 They are identical twins (but with different hairstyles) and are both voiced by Julie Kavner.
 They are Marge Simpson's older twin sisters, who both work at the Springfield Department of Motor Vehicles, and possess a strong dislike for their brother-in-law, Homer Simpson.
 Selma is the elder by two minutes, and longs for male companionship while her sister, Patty, is a lesbian.
 Kavner voices them as characters who "suck the life out of everything".
 Patty and Selma first appeared on the first ever aired Simpsons episode "Simpsons Roasting On An Open Fire", which aired on December 17, 1989.