@article{01139213,
title = {Supplement on curved flats in the space of point pairs and isothermic surfaces: A quaternionic calculus.},
journal = {Documenta Mathematica},
volume = {2},
year = {1997},
pages = {335-350},
zbl = {0892.53004},
language = {en},
url = {http://dml.mathdoc.fr/item/01139213}
}
Hertrich-Jeromin, Udo. Supplement on curved flats in the space of point pairs and isothermic surfaces: A quaternionic calculus.. Documenta Mathematica, Tome 2 (1997) pp. 335-350. http://gdmltest.u-ga.fr/item/01139213/