Errata: Self-Trapping of Optical Beams. R. Y. Chiao, E. Garmire, and C. H. Townes [Phys. Rev. Letters 13, 479 (1964)]. We thank Dr. G. A. Askarjan for pointing out prior Soviet work on beam trapping. He notes that the possibility of self-trapping of an optical beam in a medium and a radio beam in a plasma due to striction, thermal, and ionizing effects was mentioned in their article. The article by Talanof is also dedicated to this subject. Talanof studied the case of a slab-shaped beam in a plasma, but his expressions can be simply applied to electrostriction and are equivalent to those in the present work for a slab-shaped beam. The conclusion in our Letter that, in the approximation of geometric optics, the focal point develops into a line in a nonlinear material is incorrect, as pointed out by Professor L. W. Anderson. However, this does not affect the validity of the solution for trapping a cylindrical beam. Nonexistence of Parity Experiments in Multiparticle Reactions. Paul L. Csonka, Michael J. Moravcsik, and Michael D. Scadron [Phys. Rev. Letters 14, 861 (1965)]. In the eighth line after Eq. (4), after the sentence ending “...(which do change sign),” insert the following sentence: “Those scalar products which do not change sign we multiply by the pseudoscalar $$ \frac{\vec{\mathbf{k}}_{1}\cdot\vec{\mathbf{k}}_{2}\times\vec{\mathbf{k}}_{3}}{|\vec{\mathbf{k}}_{1}\cdot\vec{\mathbf{k}}_{2}\times\vec{\mathbf{k}}_{3}|}. $$”Errata: Self-Trapping of Optical Beams. R. Y. Chiao, E. Garmire, and C. H. Townes [Phys. Rev. Letters 13, 479 (1964)]. We thank Dr. G. A. Askarjan for pointing out prior Soviet work on beam trapping. He notes that the possibility of self-trapping of an optical beam in a medium and a radio beam in a plasma due to striction, thermal, and ionizing effects was mentioned in their article. The article by Talanof is also dedicated to this subject. Talanof studied the case of a slab-shaped beam in a plasma, but his expressions can be simply applied to electrostriction and are equivalent to those in the present work for a slab-shaped beam. The conclusion in our Letter that, in the approximation of geometric optics, the focal point develops into a line in a nonlinear material is incorrect, as pointed out by Professor L. W. Anderson. However, this does not affect the validity of the solution for trapping a cylindrical beam. Nonexistence of Parity Experiments in Multiparticle Reactions. Paul L. Csonka, Michael J. Moravcsik, and Michael D. Scadron [Phys. Rev. Letters 14, 861 (1965)]. In the eighth line after Eq. (4), after the sentence ending “...(which do change sign),” insert the following sentence: “Those scalar products which do not change sign we multiply by the pseudoscalar $$ \frac{\vec{\mathbf{k}}_{1}\cdot\vec{\mathbf{k}}_{2}\times\vec{\mathbf{k}}_{3}}{|\vec{\mathbf{k}}_{1}\cdot\vec{\mathbf{k}}_{2}\times\vec{\mathbf{k}}_{3}|}. $$”