A note on local periods for supercuspidal representations
  Let $G$ be a $p$-adic reductive group and $H$ a unimodular spherical subgroup of $G$. Let $\pi$ be a unitary supercuspidal representation of $G$. In this note, under a mild assumption, we show that local periods in $Hom_H(\pi,\mathbb{C})$ can be constructed by integrating the matrix coefficients of $\pi$ over $H$. 
Chong Zhang
math.RT