1. Armstrong, S., Leistner, T.: Ambient connections realising conformal tractor holonomy, math. DG/0606410 (2006)
2. Armstrong, S.: Definite signature conformal holonomy: a complete classification, math. DG/0503388 (2005)
3. Armstrong, S.: Projective holonomy II: cones and complete classifications, math. DG/0602621 (2006)
4. Armstrong, S.: Ricci holonomy: a classification, math. DG/0602619 (2006)
5. Armstrong, S.: Tractor holonomy classification for projective and conformal structures. Doctoral Thesis, Bodelian Library, Oxford University (2006).