# Early work on inverse problems

Long time ago I came across with a paper that covered early theoretical work (first half of 20th century) in the field of inverse problems. I remember there was a reference to a paper which proved that inverse problem can be solved uniquely for a spherical domain with infinitely many sources and very precise receivers distributed continuously over its surface.

Unfortunately, I cannot find neither of these papers. Does anyone know this work or anything similar?

• Is it this? – J. M. May 15 '13 at 15:11
• Guys, thanks for your help. Wolfgang got it right below. – Indalo May 17 '13 at 8:31

• But more seriously, I think the big questions have now been answered. The question was always: can you identify an $L^\infty$ coefficient from boundary data. It took a while till people could really answer this for this large space and they worked up to it, but it is now a closed case. – Wolfgang Bangerth May 18 '13 at 2:07