T. Davis, P. Davies, and C. Lineweaver. (2003)cite arxiv:astro-ph/0305121Comment: 14 pages, including 6 figures, to appear in Classical and Quantum Gravity, reference added.
D. Mulryne, D. Seery, and D. Wesley. (2009)cite arxiv:0909.2256
Comment: 24 pages, 4 colour figures; uses iopart.cls. v2: Erroneous statements
about delta N method in Sec. 2 removed. Correction to gauge transformation in
Eq. (12) brings numerical results of Sec. 4 into better agreement with the
delta N formula. Conclusions remain the same. v3: minor changes.