1.
Conformal Geometry of Surfaces in S4 and Quaternions
by Burstall, F. E., Ferus, D.,...
ISBN: 9783540430087
List Price: $49.95
2.
Twister Theory for Riemannian Symmetric Spaces (Lecture Notes in Mathematics, Vol 1424)
by Burstall, F. E., Rawnsley, ...
ISBN: 9780387526027
List Price: $33.95