The combination of the numbers 9 and 11 — whether they appeared on a microwave, a clock or a calendar — inspired author and Navy veteran Jim Serger to write a book detailing 90 Americans' memories of where they were when planes struck the World Trade Center on Sept. 11, 2001.

"I collected 90 stories from Americans all across the United States, because when you see or say or hear the term ‘nine-eleven,’ the date 9/11 automatically comes to fruition," Serger told Fox News Digital. "So, I captured those moments … because everybody remembers what they were doing on 9/11. No pun intended, but minute-by-minute — Navy, Army, teachers, professors, MBA executives … retired, Black, White, Catholic, old, young."

A portion of the proceeds from Serger's book, "9:11 A Time to Always Remember," which was published on Aug. 8, will go toward the Tunnel to Towers Foundation, a nonprofit created in honor of fallen 9/11 firefighter Stephen Siller that offers mortgage-free homes to the families of first-responders.

The book is a tribute to more than 3,000 people who died in New York City and outside of Washington, D.C., that day and how the country united after the attacks.

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One of the stories featured in his book comes from a woman who was working in the Sears Tower that day. Another is from a man who was headed into a subway station when he saw people running in the opposite direction, telling him to turn back.

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Seger himself was delivering ice — his first job after leaving the Navy more than 20 years ago — to a local grocery store when the attack happened. He remembers being called into a back room during the delivery to watch the news on a small, black-and-white TV.

The author noted that there are 730 9:11's a year when Americans can recall Sept. 11 and "how we were united as a country" on that day, which is "what everybody basically said" in his book.

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A police officer and woman covered in dust walk through wreckage after 9/11 in New York City

Police officer Mike Brennan helps a distraught woman known only as Beverly, as ash and debris cover the area following the collapse of 1 World Trade Center. (Corey Sipkin/NY Daily News Archive via Getty Images)

"Everybody was connected as a country on 9/11," Serger explained. "So, that's why I wrote this book … At 9:11 p.m., we all remember the sacrifice. We remember the firemen, the first responders [or] some stranger who was [a] friend on that day."

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One of the Americans whom Serger spoke to for his book — a Texas veterinarian — had been operating on a woman's horse when she informed him at 9:11 a.m. local time that the towers had been hit. Now, "he actually calls her every September 11th to see how she's doing," Serger said.

People stand in line to donate blood after 9/11

Los Angeles residents line-up to donate blood at the Red Cross to assist victims of the World Trade Center terrorist attack. (Steve Grayson/WireImage)

The Navy veteran recalled how unified the country became after the attack, and said Americans need to make an effort to feel that unity again without having to experience tragedy.

"As far as Montana or Texas or California, everybody was buying flags. Everybody was glued to the television set," Serger recalled. "We were thanking the first responders. We sent our veterans fine coffee, dropping off a meal, donating blood for no other reason but to do it because it's for America … We need more of that."

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Serger's book is available to purchase on the Barnes & Noble website, as well as on Amazon.

The Tunnel to Towers Foundation builds mortgage-free smart homes for Gold Star Families and the families of first responders who have died in the line of duty.