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Original reference about the interaction of two current-carrying loops in the solar chromosphere. This paper still reads quite well, after forty years, since it considers the hard problems of stability and energetics from first principles. It was a bit of a shock to re-read it and find that they were explaining chromospheric flares, which allowed them to get away with non-force-free conditions at the boundaries of their famous twisted loops. It might seem somewhat off the point, since we now more or less believe that the real action takes place in the low-beta corona, where the coronal field is all-pervasive and does not admit flux ropes with external boundaries as Gold and Hoyle propose. On the other hand, we often really do see the most powerful energy releases in very compact structures, so maybe the non-force-free domain does play a role.
Note that this concept of "loop-loop interactions" subsequently generated a lot of literature, but perhaps off the point - if the active-region corona really has low plasma beta, then any flux surface containing higher gas pressure should actually be an anti-loop, rather than a loop.
Dec. 30, 2006. There have been 149
ADS citations, or 3.31 per year up to now.
Aug. 29, 2008. In less than two years the citations have jumped to 191!
That's nice.
But one can tell from the ADS information that it's not current citations,
but probably older citations being discovered in the meanwhile.