Unpublished Dr. Seuss story 'What Pet Should I Get?' set to be released July 28

An original manuscript and sketches were found at the late children's author Dr. Seuss's La Jolla, California home, and are set to be published as picture book "What Pet Should I Get?" on July 28, according to a news release from publisher Random House.

"We believe that he wrote and illustrated 'What Pet Should I Get?' somewhere between 1958 and 1962 — as the brother and sister in the book are the same as those in his bestselling 'Beginner Book One Fish Two Fish Red Fish Blue Fish' which was published in 1960," said Cathy Goldsmith, Seuss's former art director who still works at Random House, in the release.

The manuscript was found in a box of items that belonged to Seuss, real name Theodore Geisel. The box was originally found shortly after his death in 1991, according to the release, when widow Audrey Geisel was remodeling her home. The box was set aside, before being rediscovered in 2013 by Audrey Geisel and longtime Seuss secretary and friend Claudia Prescott while clearing out his office.

"While undeniably special, it is not surprising to me that we found this because Ted always worked on multiple projects and started new things all the time — he was constantly writing and drawing and coming up with ideas for new stories," Audrey Geisel said, according to the release.. "It is especially heartwarming for me as this year also marks 25 years since the publication of the last book of Ted's career, 'Oh, the Places You'll Go!'"

The sketches for "What Pet Should I Get?" were nearly complete, according to the release.

The material that was found will also lead to two more posthumous Seuss books, according to the release. The materials of Seuss's that were found are set to be kept at UC San Diego, which houses the Dr. Seuss Collection at the Geisel Library.

The wildly popular children's author's books have sold more than 650 million copies worldwide, according to Random House.