The web site, deadline.com reports that a lawsuit over the rights to the song “Soft Kitty,” a lullaby sung on The Big Bang Theory. The lyrics for the song “Warm Kitty” were written in 1937 by the late-poet Edith Newlin, and now her daughters, Margaret Perry and Ellen Chase, are saying CBS has to pay up. The lullaby is so popular that CBS built a merchandising campaign around it, featuring Soft Kitty T-shirts, plush toys, key chains, coffee mugs and hoodies. You can get your Big Bang Theory gear here.

The song was published in a 1937 book, ‘Songs for the Nursery School.’ The rights to the book were purchased by Willis Music nearly 80 years ago and says it properly and legally licensed the song to Warner Bros. for the TV series. ASCAP, the performance rights organization, lists Warner-Olive Music, a subsidiary of the Warner Music Group, as the song’s publisher, suggesting that the rights were transferred from Willis Music.

Ms. Newlin, who was born in Indiana, died in 2004, according to the lawsuit. She studied and taught in New York before settling in Alstead, N.H., where she worked as a nursery school teacher for 35 years. Throughout her life, she wrote several children’s books and poems that were published.

One of the daughters discovered the show’s use of the lyrics in 2014 while researching her mother’s life for an article she was writing.

Here’s a great version of “Soft Kitty” by Charlie Marsden on YouTube. [wpdevart_youtube width=”640″ height=”385″ autoplay=”0″ theme=”dark” loop_video=”0″ enable_fullscreen=”0″ show_related=”0″ show_popup=”1″ thumb_popup_width=”213″ thumb_popup_height=”128″ show_title=”0″ show_youtube_icon=”0″ show_annotations=”1″ show_progress_bar_color=”red” autohide_parameters=”1″ set_initial_volume=”false” initial_volume=”100″ disable_keyboard=”0″]9AP8_LaUC4w[/wpdevart_youtube]

[wpdevart_youtube width=”640″ height=”385″ autoplay=”0″ theme=”dark” loop_video=”0″ enable_fullscreen=”1″ show_related=”0″ show_popup=”0″ thumb_popup_width=”213″ thumb_popup_height=”128″ show_title=”0″ show_youtube_icon=”0″ show_annotations=”1″ show_progress_bar_color=”red” autohide_parameters=”1″ set_initial_volume=”false” initial_volume=”100″ disable_keyboard=”0″]Ds2VWVR97J0[/wpdevart_youtube]