“Probably 150 hours of work, which can’t be reproduced before Sunday’s concert.”

Showtime at Symphony Hall is just days away, but the maestro’s notes are missing.

Staff at the Boston Philharmonic Orchestra has been searching fruitlessly this week for three annotated musical scores belonging to famed conductor Benjamin Zander, treasured documents that disappeared after his car was stolen from outside his Cambridge home last weekend.

Zander’s assistants have scanned the streets and alleys of Allston, where his white BMW was recovered last Sunday, looking for any sign of the scores. Cambridge police have also worked to identify a suspect in the case, and hope that whoever is responsible may have kept the irreplaceable music sheets, rather than tossed them in the trash, lost forever.

But the searches so far have ended on a sad note.

Now, in a last ditch effort before an upcoming musical performance, the orchestra is asking for the public’s help tracking the papers down. On Monday, the BPO shared photos of similar scores, which look a bit like textbooks, and pleaded with anyone who might have seen them to come forward.

“STOLEN,” read a tweet posted by the BPO on Twitter Monday. “Presumed to be in Allston-Brighton area.”

The tweet included a description of the missing documents — two copies of Beethoven’s Symphony No. 5 (one with its cover intact, the other without), and one spiral-bound copy of Strauss’ tone poem “Ein Heldenleben.”

The orchestra said each item is covered in notes and markings made by Zander over the years, important material that’s needed for a Boston Philharmonic Youth Orchestra performance on Sunday afternoon.

“It’s hours and hours of time,” Zander said in an e-mail to the Globe. “Every part, every entrance. … Probably 150 hours of work, which can’t be reproduced before Sunday’s concert. … I had it all done. … Suddenly I’m starting over with an unmarked score.”

The notes include countless markings that give him cues on everything from big dynamic shifts in the music, to more subtle choices that make his rendition his own.

More than that, they represent countless hours of study and craftsmanship from the 83-year-old maestro throughout his long career leading musicians from his rostrum, said Elisabeth Christensen, managing director of the BPO.

“It’s a lifetime of his work,” she said. “He’s used these same scores for decades.”

The papers in his Strauss score were so worn from use, that the orchestra’s librarian had recently rebound its tattered pages in a new spiral binding “just to hold it together,” Christensen said.

It can be extremely difficult for conductors to work without these handwritten guideposts. Christensen said leading musicians through the twists and turns of the 40-minute pieces without them is like embarking on a long journey without GPS navigation.

Because the original materials may never resurface, Zander has been feverishly trying to reproduce as many of the annotations as he can in just a few days time — a monumental feat considering the years of work he’d put into them.

“To lose all of that is devastating,” Christensen said.

The saga began last Sunday when Zander discovered that his car, which he had parked in his Brattle Street driveway with the keys inside, was stolen, according to Cambridge police reports.

Zander was dismayed — but not at the loss of the sedan.

Instead, he realized he had left a black suitcase containing the scores, conducting batons, a metronome, and an iPad, which Zander uses as a clock during performances.

Later that day, after a bystander discovered some stray items from his car, including the maestro’s business card, two of Zander’s assistants drove out to the neighborhood and were able to track down the vehicle in Allston, police said.

But both the suitcase, and the key to his BMW 330xi, were nowhere to be found.

Unfortunately for Zander, that wasn’t his last headache. On Sunday night, not long after he towed the car back to his home, the vehicle was stolen a second time. Police believe the alleged thief, or thieves, likely used the still-missing keys to brazenly drive off with the car again. Just like the first time, it was later discovered in Boston, police said.

An investigation is ongoing, but there is “no indication” that Zander was targeted specifically, Christensen said, or that the culprit was after his prized scores.

“These are old, battered scores and probably not very valuable to anybody,” she said. “Unfortunately, they’re very valuable to him.”

Although the scores might not be recovered in time, Christensen said Sunday’s performance is not in jeopardy — and the show must go on.

Because the young musicians have performed the pieces with Zander several times since rehearsals started in September, they’re already familiar with his interpretations of them.

“I’m sure that he will pull off a great performance on Sunday,” she said. “But to have to do it without his scores is adding a lot of stress and a lot of pressure for him.”