The paper by G. 't Hooft and M. Veltman, published in 1979, focuses on the calculation of one-loop radiative corrections in quantum field theory, particularly for scalar one-, two-, three-, and four-point functions. The authors derive a comprehensive set of formulas to evaluate these diagrams with arbitrary internal and external masses, addressing the complexities of gauge theories. They introduce a propagator identity and provide methods to handle real and imaginary parts of logarithms and Spence functions. The paper includes detailed derivations for one-point, two-point, three-point, and four-point functions, using Feynman parameters and projective transformations. Special attention is given to the case of soft bremsstrahlung, where an integral is simplified using techniques inspired by the propagator identity. The results are expressed in terms of Spence functions, which are useful for further calculations in quantum electrodynamics and other physical processes involving unstable particles and particles with spin.The paper by G. 't Hooft and M. Veltman, published in 1979, focuses on the calculation of one-loop radiative corrections in quantum field theory, particularly for scalar one-, two-, three-, and four-point functions. The authors derive a comprehensive set of formulas to evaluate these diagrams with arbitrary internal and external masses, addressing the complexities of gauge theories. They introduce a propagator identity and provide methods to handle real and imaginary parts of logarithms and Spence functions. The paper includes detailed derivations for one-point, two-point, three-point, and four-point functions, using Feynman parameters and projective transformations. Special attention is given to the case of soft bremsstrahlung, where an integral is simplified using techniques inspired by the propagator identity. The results are expressed in terms of Spence functions, which are useful for further calculations in quantum electrodynamics and other physical processes involving unstable particles and particles with spin.