The results of Image Trace in AI would be even better if Bethe's book was scanned, instead of being photographed from a slightly skew angle.
Sorry for the detour, but since the OP is using one of Bethe's most well known books, her is a bit of background info on him. Attached below is a scan of a Kodachrome that I took of Prof. Bethe back in the early 1970's at the dedication of the Cornell particle accelerator.
Bethe is the physicist who received the Nobel Prize for figuring out how the sun works. He's also the guy who went to sleep for the rest of my thesis exam after he was done grilling me. The attached B&W photo is another of my favorite shots of him. He's teaching his signature 3rd graduate year class "Physics 572". I'm in the photo as are two friends of mine. A third friend took the shot.
He was one of the last remaining great physicists from the utterly amazing period early in the 20th century when quantum mechanics was first developed. Prof. Bethe played a major part in this breathtaking intellectual achievement, and continued to be active and productive until well into his '90's. He lived out his last few years in the Kendal assisted living / nursing home up in Ithaca, NY until his death around 2005 at age 98 or 99. As I recall, he delivered a series of lectures on quantum mechanics to his neighbors at Kendal shortly before he passed away.
His manner was definitely "formal, old-school German" by American standards, but he would bend over backwards helping his students and was amazing in the way he could get right to the heart of any question. He is one of my heroes not only for his technical achievements, but for his stand against nuclear proliferation.
/* Sorry for the detour in this thread, but I couldn't resist giving some background info on him. You may now go back to the regularly scheduled programming.