High resolution spectroscopy over (lambda)(lambda)8500-8750 A for GAIA - IV. Extending the cool MK stars sample

A library of high resolution spectra of MK standard and reference stars, observed in support to the GAIA mission, is presented. The aim of this paper is to integrate the MK mapping of Paper I of this series as well as to consider stars over a wider range of metallicities. Radial velocities are measured for all the target stars.