Interesting stuff - looks that my mental picture of the relationship between WW1 and early spinning work was slightly out.
Anyhow, here's an inital list of references for you, if I dig anything else up I'll let you know. One or two of them may be almost impossible to obtain, but you may as well have my more or less complete referencese list...
G
D Stinton, Flying Qualities and Flight Testing of the Aeroplane, ISBN 0-632-02121-7
USAF Test Pilots School Notes, Part 10 High Angle of Attack Flight
Empire Test Pilots School, Fixed Wing Flight Test Manual, Chapter 2.8 - Spinning
UK Ministry of Defence, Stalling Post-Stalling Gyrations and Spins and Miscellaneous Flying Qualities – Post Stall Gyrations and Spins. Def-Stan 00-970 Part 1 Section 2 Leaflet 52 issue 2 Dec 99
Yangos and Yangos, Spin: Angles and Inertial Moments, Aeronautical Journal July/Aug 1981 pp270-276
T E Archer, Are you ready for LOC?, Cockpit (magazine of the Society of Experimental Test Pilots), April/May/June 1991 pp5-12
A&L Welch, Flying Training in Gliders, Published by British Gliding Association Sixth Edition 1975
UK Air Accidents Investigation Branch, Report of Fatal Accident to Aviasud Mistral G-MYST on 23 June 2001, AAIB Bulletin No: 6/2002 Ref: EW/2001/6/9
UK Air Accidents Investigation Branch, Report of Accident to Taylor J.T.1 Monoplane G-BEEW on 2 September 2001, AAIB Bulletin No: 11/2001 Ref: EW/G2001/09/03
UK Air Accidents Investigation Branch, Report of Fatal Accident to Whittaker MW6S (modified) G-MZIN on 28 March 1999, AAIB Bulletin No: 8/99 Ref: EW/C99/3/1
UK Air Accidents Investigation Branch, Report of Accident to Europa G-KWIP on 21 March 2000, AAIB Bulletin No: 4/2001 Ref: EW/C2000/3/4
UK Air Accidents Investigation Branch, Report of Fatal Accident to Jodel D112 G-BCOG on 26 July 1998, AAIB Bulletin No: 12/98 Ref: EW/C98/7/8
UK Air Accidents Investigation Branch, Report of Fatal Accident to Rallye Club 880B, G-AYKF on 26 August 1996, AAIB Bulletin No: 2/97 Ref: EW/G96/8/9
Royal Air Force, Flying AP3456
N Williams, Aerobatics, ISBN 0950454303
J S Denker, See How it Flies, http://www.monmouth.com/~jsd/how/
R Stowell, Innovations in Stall/Spin Awareness Training, Presented to (USA) Second Annual Instructor Conference, Embry Riddle Aeronautical University, April 9-10, 1999. http://www.richstowell.com/erau.htm
UK Air Accidents Investigation Board, Spectrum Microlight G-MWWY, Bulletin 3/98 EW/C97/8/8
Minutes of the 24th meeting of the Airworthiness Requirements Board Light Aircraft Committee (Nov 1998)
British Microlight Aircraft Association, Guidance on Spin Testing Microlight Aircraft, TIL 025 issue 1 dated December 1999.
G B Gratton and S J Dyde, Tucano T Mk 1 - Assessment of possible unified spin recoveries, Report D/A&E/BD/95/128, Dec 1995
Philip W Neihouse, Jacob H Lichtenstein, Jacob H Pepoon, Tail-design requirements for satisfactory spin recovery, NACA TN-1045(April 1946)
Sales literature by Ballistic Recovery Systems Inc, USA. http://www.airplaneparachutes.com/
E Arnold, Certification of Spin Resistant Aircraft, Society of Experimental Test Pilots – Report to the Profession 1999, pp58-73.
FAA, AC23-8, certification flight test guide for normal, utility and acrobatic category airplanes.