X(2175) as a resonant state of the $φK \bar{K}$ system
X(3): An Exactly Separable Gamma-Rigid Version of the X(5) Critical Point Symmetry
X-rays from Proton Bremsstrahlung: Evidence from Fusion Reactors and Its Implication in Astrophysics
XCDCC: Core Excitation in the Breakup of Exotic Nuclei
Xi production at AGS energies