Steffen Börm Jochen Garcke Approximating Gaussian Processes with <i>H</i><sup>2</sup>-Matrices. 42-53 2007 conf/ecml/2007 ECML http://dx.doi.org/10.1007/978-3-540-74958-5_8 db/conf/ecml/ecml2007.html#BormG07