The unexpected and therefore really amazing discovery of J. G. Bednorz and K. A. R32 Miiller , that certain oxide compounds enter a superconducting state at temperatures above 30 K pushed research on superconductivity into the limelight of science in general in a way that seemed reserved for a while for high-energy or particle physics only. The common interest was then even more aroused when subsequent work rather quickly established that in the same class of compounds (oxides), critical temperatures of superconductivity above R36 the boiling point of nitrogen could be achieved . It might therefore be expected, that this entire review would solely deal with superconductivity at high temperatures, i. e. , above the boiling point of hydrogen. From my point of view, however, any unexpected occurrence of superconductivity is a challenge to scientists interested either in the physics of this phenomenon or in its materials-science aspects. In this respect, the last ten years have been quite revolutionary in the sense that on various occasions, superconductivity was discovered in materials whose physical properties were not obviously favourable for adopting this ground state. This period started with the observation that homogeneous coexistence of superconductivity and magnetic order in the same material was possible. Later it was found that electrons whose effective mass was tremendously enhanced by magnetic interactions, may also form a superconducting state, namely in materials that were subsequently identified as heavy electron superconductors.

Inhalt
High superconducting transition temperatures of new rare earth ternary borides.- Superconductivity in the REX Mo6 S8.- Destruction of Superconductivity at the Onset of LongRange Magnetic Order in the Compound ErRh4 B4.- Observation of Magnetic Field Induced Superconductivity.- Unusual Properties of Magnetic Superconductors.- Superconductivity in the Presence of Strong Pauli Paramagnetism: CeCu2 Si2.- UBe13 : An Unconventional Actinide Superconductor.- Possibility of Coexistence of Bulk Superconductivity and Spin Fluctuations in UPt3.- Superconductivity and Magnetic Order in a Strongly Interacting FermiSystem: URu2 Si2.- HeavyFermion Superconductivity: Experimental Status Report.- HeavyElectron Superconductivity.- Heavyelectron superconductors, spin fluctuations, and triplet pairing.- Symmetry properties of triplet superconductors.- Superconducting classes in heavyfermion systems.- pWave Superconductivity in UBe13.- Transport and Thermal Proper-ties of HeavyFermion Superconductors: A Unified Picture.- Anisotropy of Transverse Sound in the HeavyFermion Superconductor UPt3.- New Phase Diagram for (U,Th)Be13 : A MuonSpinResonance and Hc1 Study.- Phenomenological theory of the superconductivity phase diagram of U1-x Thx Be13.- Specific Heat of UPt3: Evidence for Unconventional Superconductivity.- Anisotropy of the MagneticFieldInduced Phase Transition in Superconducting UPt3.- Mechanical Measurements of the Flux Lattice in the HeavyFermion Superconductor UPt3.- Superconductivity in a synthetic organic conductor (TMTSF)2 PF6.- ZeroPressure Organic Superconductor: Di(Tetramethyltetraselenafulvalenium)Perchlorate [(TMTSF)2 Cl04 ].- Superconductivity in a New Family of Organic Conductors.- Normalpressure superconductivity inan organic metal (BED TTTF)2 I3 [bis(ethylene dithiolo) tetrathiofulvalene triiodide].- A New Ambient Pressure Organic Superconductor (BEDTTTF)2 Cu(NCS)2 with Tc above 10 K.- Onedimensional correlations in organic superconductors: magnetism and superconductivity.- Organic Conductors and Superconductors in High Magnetic Fields.- HighTemperature superconductivity in the BaPb1-x Bi3 03 system.- Superconductivity in the BaPb1-x Bix 03 System.- Possible High Tc Superconductivity in the BaLaCuO System.- HighTc Superconductivity of LaBaCu Oxides. II. Specification of the Superconducting Phase.- Superconductivity Produced by Electron Doping in CuO2 Layered Compounds.- The Resonating Valence Bond State in La2 CuO4 and Superconductivity.- Superconductivity at 93 K in a New MixedPhase Y-Ba-Cu-O Compound System at Ambient Pressure.- Flux Trapping and Superconductive Glass State in La2 CuO4-y :Ba.- Thermally Activated Dissipation in Bi2.2 Sr2 Ca0.8 Cu2 O8+?.- SQUID Picovoltometry of YBa2 Cu3 07 Single Crystals: Evidence for a FiniteTemperature Phase Transition in the HighField Vortex State.- HighResolution Photoemission Study of the LowEnergy Excitations Reflecting the Superconducting State of BiSrCaCuO Single Crystal.- Superconductivity in the BiSrCu-0 System.- A New HighTc Oxide Superconductor without a Rare Earth Element.- Superconductivity in the rareearth-free TlBaCuO system above liquidnitrogen temperature.- Bulk Superconductivity at 125 K in T12 Ca2 Ba2 Cu3 Ox.- Superconducting Ground State of Noninteracting Particles Obeying Fractional Statistics.- Author Index.