Key points are not available for this paper at this time.
The work of Finkelstein, Kruskal, Graves and Brill, Carter, and Boyer and Lindquist on the extension and schematic representation of 2-dimensional metrics is systematized and generalized. As a result, a number of extensions may be found by inspection. Some well-known examples are given, and the technique is applied to the ``soluzioni oblique'' of Levi-Civita.
Martin Walker (Sat,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: