NEW ORLEANS (AP) — Chances for adding to a significant part of the National World War II Museum’s collection are dwindling by the day, and the museum is stepping up efforts to capture oral histories it fears will be lost with an aging corps of veterans.

The museum’s foundation is oral histories of the men and women who served in the armed forces and civilians who worked to support them at home and abroad. Their numbers — once in the millions — are shrinking rapidly. Even the youngest soldier at the war’s end in 1945 would now be in his or her mid-80s.

The museum has more than 7,000 oral histories on video or audiotape — and spectacular displays of war machines. But the oral history collection has gaps, research services manager Seth Paridon said.

Paridon would like to expand stories of air crews sent to bomb refineries in Ploesti, Romania, which provided more than one-third of the oil for Axis forces. The museum has found only three veterans of that mission so far.

And he is especially interested in survivors of the Aug. 1, 1943, Operation Tidal Wave raid.

Tidal Wave was one of the Army Air Force’s deadliest single missions: 53 planes and 660 men were lost from a force of more than 150 B-24 Liberator bombers launched from Libya.

“It’s tough finding guys who A, survived, B, who can remember and C, are willing to talk,” Paridon said.

It was a daytime, low-level raid, even though a defecting Romanian pilot had reported five days earlier that the area was bristling with anti-aircraft guns. After a 1942 Allied raid that met little opposition, the Germans had built a massive defense.

Romania, along with Hungary, Bulgaria and several puppet states carved from the conquered Yugoslavia, provided troops and material resources to the German war machine.

Operation Tidal Wave will be featured as the museum opens a new building next fall with exhibits about the war in Europe.

Historian Stephen Ambrose’s audio interviews are the museum’s foundation, covering D-Day and the European campaign.

“We immediately started to branch out and to do more — not just Normandy but the Pacific, Midway, Guadalcanal, Iwo Jima and other areas,” Paridon said.

Current oral histories are videotaped. Most exhibits include terminals that play videos in which veterans describe their experiences.

Paridon said civilian women who staffed Red Cross Clubmobiles — buses and trucks equipped with books, records, record players, coffee urns and doughnut machines to help boost morale — will be at least as hard to find as veterans of Operation Tidal Wave, since they were typically older than the soldiers.

“If you’re looking for a GI who’s now 93, these ladies would be near 100,” Paridon said.

The first Clubmobiles were buses that traveled to bases in Britain. Trucks were used in France, Belgium, Luxembourg and Germany for groups in the Army’s rear echelon in 1944 and 1945. Three Red Cross staffers were assigned to each Clubmobile.

Another largely missing civilian group is the scientists who worked on the Manhattan Project developing the atomic bomb.

He’d also like to interview Navy Seabees who built harbors and airstrips, Coast Guard sailors who protected convoys, carried supplies and piloted landing craft, and merchant seamen who ferried supplies to war zones.

He’s looking for stories from Pacific veterans, including campaigns in the Philippines, Guam and New Guinea; armored division combat veterans in the European and Pacific theaters; those who were in the invasion of Anzio; and members of the 15th Air Force and 28th Infantry Division.

Very few 28th Infantry members survived Hurtgen Forest in 1944, where the Army chose to try to clear the forest of German troops rather than go around the dense forest.

“The GIs called it the meat grinder. It was perfect for defense,” Paridon said.

The veterans can be difficult to find. Many aren’t technologically savvy and may not know the museum exists. Paridon said the museum tries to reach those veterans with a how-to guide for families to capture oral histories.

“The best advice I can give people who want to do oral histories for their families, or even for us, is to let the veteran talk. Ask questions but ask open-ended questions. Chances are they’re going to reveal things you never knew, even if it’s your grandfather,” Paridon said.