Piano Man (song)
"Piano Man" is a song written and performed by American singer-songwriter Billy Joel. His first single in North America, it was included on Joel's 1973 album of the same name and later released as a single on November 2, 1973. The song is sung from Joel's point-of-view as a piano player at a bar, reminiscing about his experiences there and the people he encountered. "Piano Man" is based on Joel's real-life experiences as a lounge musician in Los Angeles from 1972–73, which he had decided to pursue in an effort to escape his contracted New York City-based record company at the time, Family Productions, following the poor commercial performance of the album "Cold Spring Harbor". Joel describes various characters, including a bartender named John and a "real-estate novelist" named Paul, all based on real-life individuals.
Piano Man (song)
Joel's first major hit and his signature song, "Piano Man" peaked at #25 on the "Billboard" Hot 100 chart in April 1974. Following Joel's breakthrough as a popular musician with the release of "The Stranger", it became one of his most well-known songs. It is now a highlight of Joel's live shows, where he usually allows the audience to sing the chorus. In 2015, the Library of Congress selected "Piano Man" for preservation in the National Recording Registry for its "cultural, historic, or artistic significance."
The Entertainer (song)
"The Entertainer" is a single by singer Billy Joel released as the only single from his 1974 album "Streetlife Serenade". The song peaked at #34 on the US charts, a Top 40 hit for Joel that year. The song is a cynical and somewhat satirical look at the fleeting fame of a musician and fickle public tastes ("Today I am your champion / I may have won your hearts / But I know the game / You'll forget my name / And I won't be here / in another year / if I don't stay on the charts"); this theme would be examined in the later song "It's Still Rock and Roll to Me". 
The Entertainer (song)
Another verse in the song references the shortening of Joel's song, "Piano Man", from 5 minutes and 38 seconds to 3 minutes and 5 seconds to fit a radio slot, referenced by the lyrics "It was a beautiful song, / but it ran too long / If you're gonna have a hit, you gotta make it fit / So they cut it down to 3:05." Additionally, the timing printed on the label of the 7" release of "The Entertainer" was 3:05, although the actual 45 length was 3:11 (while the album length was 3:41). In the single version, Verse 3 (which starts at 1:02 in the album version) is edited out, and Verse 2 (which starts at 0:40) contains a steel guitar in its second half, which is actually featured in the second half of the "third" verse in the album version; indeed, on the single mix, the instrumental crescendo of the album version is anticipated by bringing the fuller instrumentation of Verse 3 under the vocals of Verse 2. As a result of this, the slightly emptier original instrumentation of Verse 2 (which includes a downward slide on the synth) and the vocals of Verse 3 are completely omitted, while the instrumentation of Verse 3 (featuring the steel guitar) does appear, but earlier.

Question: The Entertainer references what other song, released in 1973?
Answer: Piano Man