A documentary titled "The Richest Songs In The World" picked two Righteous Brothers classics as some of the biggest money making songs of all time.According to DigitalSpy.com, the duo's classics "You've Lost that Lovin' Feelin'" and "Unchained Melody" appear at #3 and #5, respectively on the list. The documentary compiled the list based on the amount of publishing royalties the songs have earned over the years.

Other classics making the list include The Beatles' "Yesterday" at #4, Ben E. King's "Stand by Me" at #6 and Roy Orbison's "Oh, Pretty Woman" at #9.

The top earning song of all time is "Happy Birthday to You," written by sisters Patty Hill and Mildred J. Hill in 1893.

Three Christmas songs, "White Christmas", "Santa Claus Is Coming to Town" and "The Christmas Song (Chestnuts Roasting on an Open Fire)" were also in the Top 10.