Independent Subspace Analysis and Topographic ICA Can anyone recommend the best references for independent subspace analysis (ISA). I have read 'Multidimensional Independent Component Analysis' by Cardoso and would like to know of any modern, solid (i.e. generally accepted to work) approaches.

If you have implemented ISA before how did it perform?
Read this paper about ISA: http://www.cs.helsinki.fi/u/ahyvarin/papers/ESANN06.pdf

and this one about topographic ICA: http://www.cs.helsinki.fi/u/ahyvarin/papers/NC01_TICA.pdf

Hyvärinen is the author of the FastICA algorithm.

PS. 

By the way, you might want to look at ICASSO (http://research.ics.aalto.fi/ica/icasso/), if you are not already familiar with it.