Phil Everly, whose close-harmony singing made the Everly Brothers rank among the elite in the pop music world of the 1950s and early 1960s, died on Friday at the age of 74.

According to reports, Everly died at a Burbank, Calif., hospital due to complications from chronic obstructive pulmonary disease.

“We are absolutely heartbroken,” Patti Everly, wife of Phil Everly, told the Los Angeles Times. “He fought long and hard.”

Presidential historian Michael Beschloss tweeted a concert poster of the Everly brothers saying, “Note that Phil Everly (1939-2014) & brother Don got billing over Stones in England 50 years ago.”

The Everly Brothers, Phil and Don, influenced 1960s-era artists like the Beatles, the Beach Boys, Simon & Garfunkel and many others.

The Everly Brothers had nearly three dozen hits on the Billboard Hot 100 single charts, which included their songs like “Cathy’s Clown,” “Wake Up Little Susie,” “Bye Bye Love,” “When Will I Be Loved” and “All I Have To Do Is Dream.”

The two brothers had an onstage break up during a concert at Knott’s Berry Farm in California in 1973 after 16-years of hits, they reunited in 1983.  

“Don and I are infamous for our split,” Phil once said to the Time magazine, “but we’re closer than most brothers. Harmony singing requires that you enlarge yourself, not use any kind of suppression. Harmony is the ultimate love.”

Philip Everly was born Jan. 19, 1939, in Chicago, the son of Ike and Margaret Everly, two country musicians.

According to reports, singer Linda Ronstadt, who had a big hit in 1975 with “When Will I Be Loved,” which Phil wrote, said: “they were both such good singers – they were one of the foundations, one of the cornerstones of the new rock ‘n’ roll sound.”