JEFFERSON COUNTY, Colo. — For one library patron, it took 40 years to perfect the paper airplane.

The Jefferson County Public Library says a book entitled "The Paper Airplane Book," by Seymour Simon, was returned Friday, exactly 40 years after its due date.

The book was due Nov. 8, 1979, to the Lakewood Regional Library. It was returned to the same library, which still serves patrons at West 20th Avenue and Miller Street.

"We'd like to return this book," said the patron, according to Jeffco Public Library. "It's a little overdue."

The book still had its original checkout card.

Even though the book is back home, don't bother trying to check it out. This copy was no longer in the Jefferson County Public Library system and has officially been taken out of circulation.

A spokesperson for the library system said they're trying to find the person who returned the book, to give it back to them as a gift.

But don't despair. If you'd like to learn how to fold paper airplanes from author Seymour Simon, you can get a different copy through the Prospector system, which allows patrons to check out books from other library systems in Colorado and beyond.

For instance, the Denver Public Library has three copies available, along with dozens of other titles by Simon, a prolific children's book writer who tackled multitudinous science topics from elephants to earthquakes to exoplanets for his young audience.

If you're wondering what the overdue fees are on a book that is approximately 14,600 days overdue, at 5 cents per day, it's about $730. The patron got a pass on paying it, though.

"We called it even because it's good content," according to the library system. "We figured the amount of guilt they must've felt was enough."

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