These reviews traced the history of SSF and discussed various developments since historical time.
Since then, there has been a vast change in the scenario of SSF research all over the world.
Tracing the history from the period since these were published revealed significant developments in SSF.
During this period (1991–1999), more than 1000 publications have appeared in various journals, proceedings and books, apart from four important publications in book form [4–7].
A few reviews have also been presented discussing some particular features of SSF from time to time [8–13].
The latest in this has been a special one by CW Hesseltine [14] as the Thom Award Address, which is reprinted from his work in 1981.