Over twenty years since the appearance of volume 1 of this prestigious series, the rare earths continue to perplex, if not mystify us. There is no doubt that in the next breakthrough to a higher level of human understanding of nature, the rare earth elements and their compounds will play an important part in its elaboration. The reviews contained in this 26th volume continue this quest.

Three of the chapters deal with various aspects of the magnetic behaviours of the lanthanide metals and some of their compounds, while the fourth is concerned with the photoelectron spectroscopy of the anomalous f (heavy fermion) systems in cerium and uranium compounds.

The first chapter presents information and results gleaned from X-ray scattering studies on the magnetic lanthanide metals, intra lanthanide alloys, a few intermetallic compounds, intra lanthanide superlayers and thin films.

Chapter two is concerned with the use of static pressure and alternating mechanical stresses and their effects to study the magnetic properties of the lanthanide metals, alloys and compounds.

This is followed by an examination of magnetic systems which are close to the critical conditions for the appearance of magnetic ordering. The authors note that itinerant electron metamagnetism was predicted over 35 years ago, but that the major advances were only discovered over the past decade.

One of the prime research tools for understanding 4f and 5f systems is photoelectron spectroscopy and early work is this field was plagued by the lack of single crystals, the poor quality of polycrystalline samples and inadequate theories to interpret photoelectron spectra. This has however changed, and new developments are reviewed in the last chapter.