Peter Paul and Mary

Peter, Paul and Mary, the trio that became stars of the 1960s folk music boom, and had enduring hits with their covers of Bob Dylan's "Blowin' in the Wind," Pete Seeger's "Where Have All the Flowers Gone" and songs of their own like "Puff the Magic Dragon," have assembled a three-pronged celebration of their 50th anniversary - or at least, what the surviving members, Noel Paul Stookey and Peter Yarrow (Mary Travers died in 2009) are calling their 50th anniversary.

A new album, "Discovered: Live in Concert," will include 13 songs the group performed in concert but never recorded in the studio. The recordings were made at a handful of concerts in the 1980s, and rediscovered when the group was compiling "Carry It On," its 2004 career overview. Only one of the songs, "Mi Caballo Blanco," was included in that set. The remaining 12 - among them, "Midnight Special," "You Can Tell the World" and "Cactus in a Coffee Can" - are previously unissued. Rhino will release the set on Nov. 17.

Also due in November is a coffee table book, "Peter, Paul and Mary: 50 Years in Life and Song" (Imagine/Charlesbridge). And on Dec. 1, PBS will air a documentary, "50 Years With Peter, Paul and Mary," which promises to include archival footage from the group's appearances at Civil Rights and antiwar demonstrations.

Exactly why this fall should be regarded as the group's 50th anniversary, however, is a mystery. The trio was formed in 1961, and released its first album, "Peter, Paul and Mary," in 1962. That would make it closer to 54 years.

"Yeah, it's kind of an inside joke," Mr. Stookey explained in an email. "Do you remember the PP&M album called 'Late Again'? We have a reputation for taking longer than expected because we're meticulous and sensitive to each other's reservations. We never did a thing as a trio that all three of us didn't agree on. We finally agreed on this book - Mary in absentia, mostly, though much of her writings contributed to the text, as well as our recollections of conversations and attitudes."

- The New York Times, October 21, 2014