Bremsstrahlung energy spectra induced by beta ray from radionuclides3H, 63Ni, 14C, 147Pm, 90Sr, 32P and90Yare calculated by using numerical data of radiation yield published by Berger et. al. and compared with those obtained from classical approximate expressions of Wu and Segré. The results for3H, 63Ni, 14C and147Pm are in good agreement with those from Segré's, while spectra from such as32P and90Y are similar to those obtained by using Wu's expression. The result for90Sr is in fair agreement with those from Wu's and Segré's.