These are Amazon's bestselling books of 2021 so far

A nonfiction book about "[the] counter-revolution to the American Revolution." A fantasy novel about a woman who finds a library filled with books about lives she might have led. Picture books about loving polar bears, bedtime-ready critters and one especially peckish caterpillar. These wildly different titles are all among Amazon's best-selling books of 2021.

Not that you need an excuse to buy a book, but with Black Friday looming, and gift ideas at a premium, here's an overview of the 10 best-selling titles for the year to date, per the Amazon bestseller list. The rankings are current as of Oct. 20.

And, yes, at last look, new, physical copies of each title (save one) were in stock from Amazon. (Take that, supply-chain issues!) Prices and availability are current as of publication.

1. "American Marxism"

This entry by Fox News host, syndicated radio star and attorney Mark R. Levin ("Life, Liberty & Levin") vaulted to the top of the annual sales charts after being released in mid-July. (And, actually, as reported by the Washington Times, it was moving up Amazon's rankings even in advance of its street date.) In "American Marxism," Levin makes the case that, per the publisher, "core elements of Marxist ideology are now pervasive in American society and culture." The American Spectator called it "exactly the right book at the right time."

"American Marxism" (Hardcover), $17

$17 at Amazon

"American Marxism" (Kindle Edition), $15

$15 at Amazon

2. "Atomic Habits: An Easy & Proven Way to Build Good Habits & Break Bad Ones"

Book buyers have had a habit of buying this self-help title since it was published in 2018. As its title suggests, "Atomic Habits" is about habits: how to form good ones, how to break bad ones -- and how to put yourself on the path to the good ones in as little as two minutes a day (via "The Two-Minute Rule"). US News & World Report called author James Clear's recipes for success one of its "10 best business books every entrepreneur should read."

"Atomic Habits: An Easy & Proven Way to Build Good Habits & Break Bad Ones" (Hardcover), $12

$12 at Amazon

"Atomic Habits: An Easy & Proven Way to Build Good Habits & Break Bad Ones" (Kindle Edition), $16

$15 at Amazon

3. "The Four Agreements: A Practical Guide to Personal Freedom, A Toltec Wisdom Book"

Championed by Ellen DeGeneres and Oprah Winfrey, "The Four Agreements" went from obscurity to overnight success some 20 years ago. Still a bestseller, author Don Miguel Ruiz's spiritual tome is based on way-of-life teachings passed down from the Toltec culture that the author learned growing up in Mexico. Seven-time Super Bowl champ Tom Brady is among the book's fans: He's called it "kind of a mantra for my life."

Gift-givers, take note: As of publication, physical copies were only available from Amazon via third-party sellers. Prices vary. Amazon was offering the book directly as a Kindle edition, or as an audiobook (accessed via an Audible Premium Plus subscription, for $7.95 a month).

"The Four Agreements: A Practical Guide to Personal Freedom, A Toltec Wisdom Book" (Kindle Edition), $6

$6 at Amazon

4, "The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma"

"The Body Keeps the Score," by trauma specialist and psychiatrist Bessel van der Kolk, is a look at how trauma remaps the brain. A bestseller upon its release in 2014, "[d]uring the pandemic, " the Atlantic observed in October, the title "seems more in demand than ever."

"The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma" (Paperback), $11

$11 at Amazon

"The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma" (Kindle Edition), $12

$11 at Amazon

5. "The Boy, the Mole, the Fox and the Horse"

Published in 2019, "The Boy, the Mule, the Fox and the Horse" is the first title from cartoonist and book illustrator Charlie Mackesy. In the New York Times, Elisabeth Egan described Mackesy's work as a "fable intended for people of all ages."

"The Boy, the Mule, the Fox and the Horse," Egan wrote, "combines the simplicity of 'The Giving Tree,' the magic of 'The Velveteen Rabbit' and the curiosity of Paddington."

On Amazon, it's a top-seller among buyers looking for self-help, philosophy and/or literary graphic novels.

"The Boy, the Mole, the Fox and the Horse" (Hardcover), $14

$14 at Amazon

"The Boy, the Mole, the Fox and the Horse" (Kindle Edition), $12

$12 at Amazon

6. "If Animals Kissed Good Night"

Upon its release in 2008, Kirkus Books praised this children's picture book as something "[s]ure to send readers off to a gentle goodnight... after a kiss, of course." Written by Ann Whitford Paul, with illustrations by David Walker, "If Animals Kissed Good Night" has remained a staple of the bedtime-story genre.

"If Animals Kissed Good Night" (Board Book), $4

$4 at Amazon

7. "I Love You to the Moon and Back"

Published in 2015, "I Love You to the Moon and Back" is another favorite bedtime read. The Amelia Hepworth-penned tale, featuring illustrations by Tim Warnes, tells the gentle tale of the day in the life of a polar bear and her cuddly cub.

"I Love You to the Moon and Back" (Board Book), $4

$4 at Amazon

8. "The Four Winds: A Novel"

The latest novel from author Kristin Hannah ("The Nightingale"), "The Four Winds" follows a woman from Texas to California during the bleak years of the Dust Bowl and Great Depression. Wrote Elisabeth Egan in the New York Times shortly before the book's February publication, "Its message is galvanizing and hopeful: We are a nation of scrappy survivors."

"The Four Winds: A Novel" (Hardcover), $12

$12 at Amazon

"The Four Winds: A Novel" (Kindle Edition), $15

$15 at Amazon

9. "The Very Hungry Caterpillar"

When Eric Carle passed away in May at the age of 91, his survivors included generations of readers raised on his library of illustrated children's classics, including "The Very Hungry Caterpillar." Published in 1969, the hands-on book about transformation (and food!) remains a favorite and then some: More than 55 million copies are said to have been sold worldwide.

"The Very Hungry Caterpillar" (Board Book), $5

$5 at Amazon

"The Very Hungry Caterpillar" (Kindle Edition), $9

$9 at Amazon

10. "The Midnight Library: A Novel"

Shortly after its release in 2020, "The Midnight Library" was pegged by the Washington Post as one its "15 feel-good books guaranteed to lift your spirits." The fantastical novel by Matt Haig ("How to Stop Time") is about a grieving cat owner who, in an attempt to take her own life, is transported to the Midnight Library, where she can read about all the alternate lives she could have led had she made different choices.

"The Midnight Library: A Novel" (Hardcover), $13

$13 at Amazon

"The Midnight Library: A Novel" (Kindle Edition), $11

$11 at Amazon