TOUCHDOWN: References needed

[Weiss]

I think the original paper is:

R.H. Don et al. 'Touchdown' PCR to circumvent spurious priming 
during gene amplification. Nucleic Acids Res 19: 4008 (1991)

some other papers dealing with touchdown are:

Ault et al. J Virol Methods 46: 145-156 (1994)
Ireland et al. J Med Virol 40: 96-101 (1993)
Kusser et al. PCR Methods Appl 2: 250-252 (1993)

Hope this helps, 
Christoph Kruell