1.

Mansouri, Reza, and Nozari, Koruosh. (2000). *A New Distributional Approach to Signature Change*, *Gen. Rel. Grav.*
**32**, 253–269.

2.

Dray, Tevian, Manogue, Corinne A., and Tucker, Robin W. (1991). *Particle Production from Signature Change*, *Gen. Rel. Grav.*, **23**, 967–971.

3.

Dray, Tevian, Manogue, Corinne A., and Tucker, Robin W. (1993). *The Scalar Field Equation in the Presence of Signature Change*, *Phys. Rev. D*
**48**, 2587–2590.

4.

Hellaby, Charles, and Dray, Tevian. (1994). *Failure of Standard Conservation Laws at a Classical Change of Signature*, *Phys. Rev. D*
**49**, 5096–5104.

5.

Ellis, G., Sumeruk, A., Coule, D., and Hellaby, C. (1992). *Change of Signature in Classical Relativity*, *Class. Quant. Grav.*
**9**, 1535–1554.

6.

Ellis, G. F. R. (1992). *Covariant Change of Signature in Classical Relativity*, *Gen. Rel. Grav.*
**24**, 1047–1068.

7.

Carfora, Mauro, and Ellis, George. (1995). *The Geometry of Classical Change of Signature*, *Intl. J. Mod. Phys. D*
**4**, 175–188.

8.

Hayward, Sean A. (1994). *Weak Solutions Across a Change of Signature*, *Class. Quantum Grav.*
**11**, L87–L90.

9.

Tevian Dray, Manogue, Corinne A., and Tucker, Robin W. (1995). *Boundary Conditions for the Scalar Field in the Presence of Signature Change*, *Class. Quantum Grav.*
**12**, 2767–2777.

10.

Hayward, Sean A. (1995). “*Failure of Standard Conservation Laws at a Classical Change of Signature*,” *Phys. Rev. D*
**52**, 7331–7332.

11.

Hellaby, Charles, and Dray, Tevian. (1995). *Reply Comment: Comparison of Approaches to Classical Signature Change*, *Phys. Rev. D*
**52**, 7333–7339.

12.

Hayward, Sean A. (1992). *Signature Change in General Relativity*, *Class. Quant. Grav.*
**9**, 1851–1862; erratum: (1992). *Class. Quant. Grav.*
**9**, 2543. 4We note that the cosmological constant jumps from 3/α
_{–}
^{2}
to 3 α
_{+}
^{2}
in the above example, but this is not a problem, as discontinuities in the matter occur with the usual (Lorentzian to Lorentzian) boundary conditions, whereas at a signature change the whole nature of physics changes and causality suddenly appears. Indeed a jump is a much weaker singularity than a surface layer, which MN allow (top half of p. 266). 5 It should be emphasised that the surface effects found in [4] are delta functions in the conservation laws, not in the Einstein ?matter tensor. **Dray, Ellis, and Hellaby 1046**

13.

Kossowski, M., and Kriele, M. (1993). *Smooth and Discontinuous Signature Type Change in General Relativity*, *Class. Quant. Grav.*
**10**, 2363–2371.

14.

Dray, Tevian (1996). *Einstein' Equations in the Presence of Signature Change*, *J. Math. Phys.*
**37**, 5627–5636.

15.

Dray, Tevian, Ellis, George, Hellaby, Charles, and Manogue, Corinne A. (1997). *Gravity and Signature Change*, *Gen. Rel. Grav.*
**29**, 591–597.

16.

Darmois, G. (1927). Mémorial des Sciences Mathématiques, Fascicule 25, Gauthier-Villars, Paris.

17.

Waseem Kamleh, *Signature Changing Space-times and the New Generalised Functions*, grqc ?0004057.

18.

Dray, Tevian, and Hellaby, Charles. (1996). *Comment on 'smooth and Discontinuous Signature Type Change in General Relativity'*, *Gen. Rel. Grav.*
**28**, 1401–1408 (1996).