By Desiree Salas (media@latinospost.com) | First Posted: Dec 30, 2015 05:00 AM EST

Remember the song that "The Big Bang Theory's" Sheldon wanted sung to him at bedtime? Turns out the lyrics aren't exactly original, as alleged by a lawsuit filed by the heirs of the writer of the song/poem.

"On Monday, a lawsuit was filed by the daughters of Edith Newlin, a New Hampshire teacher who originally wrote a poem about a 'soft kitty"'in the 1930s," Variety reported. "The heirs of Newlin, who died in 2004, claim in the copyright infringement suit that 'Big Bang' has used the lyrics to the song without permission."

The lawsuit stated that the hit TV series had used the lyrics on no less than 8 episodes without permission since March 2008. The lyrics to the said song, as performed on the show, goes as follows:

"Soft kitty, soft kitty,

Little ball of fur,

Sleepy kitty, happy kitty,

Purr! Purr! Purr!"

Newlin's version, USA Today said, was titled "Warm Kitty," with the poem consequently beginning with the phrase "warm kitty." The rest of the lyrics are similar to those used in the series.

"The lawsuit, seeking unspecified damages from the sitcom's producers and distributors, also says the lyrics have been used in the series' merchandising with shirts, sweatshirts, pajamas and more products featuring the lyrics," Variety went on.

Further, the claim also accused the defendants as having made the lyrics appear as if it were created by the comedy show's producers themselves.

"The suit maintains that Warner Bros. sought permission in 2007 from Willis Music Co., a company that previously published the lyrics in a book titled 'Songs for the Nursery School,'" the entertainment news source noted. "According to Newlin's daughters, Willis Music Co. authorized the use of lyrics without consultation or permission."

Newlin's daughters, Ellen Newlin Chase and Margaret Chase Perry, both in their 70s, had not watched "Big Bang" and was unaware of the lyrics usage despite the popularity of the show. They only learned of the show's usage of the words August 2014, when Chase "was researching her mother's history for an article she was writing and came across a blog post discussing the use of the lyrics on the show," USA Today said.

"The 'Soft Kitty' lyrics are among the best-known and most popular aspects of 'The Big Bang Theory,'" the daughters' legal claim stated. "They have become a signature and emblematic feature of the show and a central part of the show's promotion."

Indeed, the ditty had gained a following in the wake of the show's popularity, with CBS creating a host of merchandise that featured elements of the song.

"The song was first sung on show's 'The Pancake Batter Anomaly' episode in 2008, and has subsequently been sung on 'The Vegan Renormalization,' 'The Electric Can Opener Fluctuation,' 'The Adhesive Duck Deficiency,' 'The Cruciferous Vegetable Amplification,' 'The Rhinitis Revelation,' 'The Proton Resurgence', and 'The Anxiety Optimization' episodes," Deadline recalled.

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