Question: Which of those that discovered Runge's phenomenon  was a German mathematician, physicist, and spectroscopist.?

Context paragraphs:
Paul Guldin: Paul Guldin (original name Habakkuk Guldin; 12 June 1577 (Mels) – 3 November 1643 (Graz)) was a Swiss Jesuit mathematician and astronomer.  He discovered the Guldinus theorem to determine the surface and the volume of a solid of revolution.  (This theorem is also known as the Pappus–Guldinus theorem and Pappus's centroid theorem, attributed to Pappus of Alexandria.)  Guldin was noted for his association with the German mathematician and astronomer Johannes Kepler.  Guldin composed a critique of Cavalieri's method of Indivisibles.

Werner Boy: Werner Boy (] ; 4 May 1879 − 6 September 1914) was a German mathematician.  He was the discoverer and eponym of Boy's surface—a three-dimensional projection of the real projective plane without singularities, the first of its kind.  He discovered it in 1901 after his thesis adviser, David Hilbert, asked him to prove that it was not possible to immerse the real projective plane in three-dimensional space.  Boy sketched several models of the surface, and discovered that it could have 3-fold rotational symmetry, but was unable to find a parametric model for the surface.  It was not until 1978 that Bernard Morin found the first parametrisation, with the aid of computers.

Carl David Tolmé Runge: Carl David Tolmé Runge (] ; 30 August 1856 – 3 January 1927) was a German mathematician, physicist, and spectroscopist.

Iris Runge: Iris Anna Runge (1 June 1888 – 27 January 1966) was a German applied mathematician and physicist.

Victor Schumann: Victor Schumann (December 21, 1841 – September 1, 1913) was a physicist and spectroscopist who in 1893 discovered the vacuum ultraviolet.

Runge's phenomenon: In the mathematical field of numerical analysis, Runge's phenomenon is a problem of oscillation at the edges of an interval that occurs when using polynomial interpolation with polynomials of high degree over a set of equispaced interpolation points.  It was discovered by Carl David Tolmé Runge (1901) when exploring the behavior of errors when using polynomial interpolation to approximate certain functions.

Runge's theorem: In complex analysis, Runge's theorem (also known as Runge's approximation theorem) is named after the German mathematician Carl Runge who first proved it in the year 1885.  It states the following:

Barbara Niethammer: Barbara Niethammer (born 1967) is a German mathematician and materials scientist who works as a professor at the Hausdorff Center for Mathematics at the University of Bonn.  Her research concerns partial differential equations for physical materials, and in particular the phenomenon of Ostwald ripening by which particles in liquids grow over time.

P-adic quantum mechanics: "p"-adic quantum mechanics is a relatively recent approach to understanding the nature of fundamental physics.  It is the application of p-adic analysis to quantum mechanics.  The p-adic numbers are a counterintuitive arithmetic system that was discovered by the German mathematician Kurt Hensel in about 1899.  The closely related adeles and ideles were introduced in the 1930s by Claude Chevalley and André Weil.  Their study has now transformed into a major branch of mathematics.  They were occasionally applied to the physical sciences, but it wasn't until a publication by the Russian mathematician Igor Volovich in 1987 that the subject was taken seriously.  There are now hundreds of research articles on the subject, along with international journals as well.

Runge–Kutta–Fehlberg method: In mathematics, the Runge–Kutta–Fehlberg method (or Fehlberg method) is an algorithm in numerical analysis for the numerical solution of ordinary differential equations.  It was developed by the German mathematician Erwin Fehlberg and is based on the large class of Runge–Kutta methods.

Supporting paragraphs: Runge's phenomenon Carl David Tolmé Runge
Answer: Carl David Tolmé Runge