Book excerpt: The Hadron Mass Spectrum covers the proceedings of the Rheinfels Workshop on the Hadron Mass Spectrum, held in St. Goar, Germany on September 3-6, 1990. The book focuses on the processes, methodologies, and reactions involved in hadron spectroscopy. The selection first offers information on strange meson and strangeonium spectroscopy and strangeonium production from LASS. The book also takes a look at the status of strange meson spectroscopy, including status of the spectroscopy, systematics of the level structure, and contributions from LASS. The publication examines the scalar meson enigma and two photon couplings of scalar and tensor mesons. The manuscript also touches on rhoprimes, omegaprimes, and glueballs; meson production mechanisms and selection criteria for cryptoexotic states; and light meson spectroscopy and threshold effects. The selection is a dependable reference for readers interested in hadron mass spectrum.