A resonance seen in ${{\mathit \Lambda}_{{{b}}}^{0}}$ $\rightarrow$ ${{\mathit P}_{{{c}}}^{+}}{{\mathit K}^{-}}$, then ${{\mathit P}_{{{c}}}}$ $\rightarrow$ ${{\mathit J / \psi}}{{\mathit p}}$, with a significance of 12 standard deviations. The ${{\mathit J / \psi}}{{\mathit p}}$ quark content is ${{\mathit u}}{{\mathit u}}{{\mathit d}}{{\mathit c}}{{\overline{\mathit c}}}$, a pentaquark. See also the ${{\mathit P}_{{{c {{\overline{\mathit c}}}}}}{(4380)}^{+}}$. In the best amplitude fit, the two states have opposite parity, one having $\mathit J = 3/2$, the other $\mathit J = 5/2$. Extraction of the pentaquark signals requires some understanding of the dominant ${{\mathit K}^{-}}{{\mathit p}}$ background. AAIJ 2015P used a model-dependent approach. AAIJ 2016AG reanalyzed the data making minimal assumptions about the ${{\mathit K}^{-}}{{\mathit p}}$ background, and thus confirmed the strong significance of the pentaquark signals.