We calculate some invariants determined by the spectrum of the Jacobi operator $J$ of $n$-dimensional totally real submanifolds of the quaternionic projective space $QP^n$ and we use such invariants to characterize parallel submanifolds of $QP^n$.
"Spectral Geometry of the Jacobi Operator of Totally Real Submanifolds of $QP^n$." Tokyo J. Math. 28 (1) 109 - 125, June 2005. https://doi.org/10.3836/tjm/1244208283