All sources cited in Subject 020 AGK — with current direct links (as of May 2026).
EASA — certification and operations
- CS-23 (Certification Specifications for Normal, Utility, Aerobatic and Commuter Aeroplanes) — https://www.easa.europa.eu/en/document-library/certification-specifications
- CS-25 (Large aeroplanes — for comparison with CS-23) — same URL
- Easy Access Rules for Part-NCO (operations) — https://www.easa.europa.eu/en/document-library/easy-access-rules
- EASA SIBs / ADs relevant to your aircraft — https://ad.easa.europa.eu/
Manufacturers
- Lycoming Operator's Manuals — https://www.lycoming.com/content/operators-manuals
- Continental Motors Operator's Manuals — https://www.continental.aero/general-aviation/operator-information
- Hartzell Propeller — https://hartzellprop.com/owner-resources/
- McCauley Propeller Systems — https://www.mccauley.textron.com/owner-support
FAA handbooks (free, excellent teaching material)
- FAA-H-8083-25 Pilot's Handbook of Aeronautical Knowledge — https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak
- FAA-H-8083-3 Airplane Flying Handbook — https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook
- FAA-H-8083-15 Instrument Flying Handbook — https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_flying_handbook
ICAO
- ICAO Annex 8 (Airworthiness of Aircraft)
- ICAO Annex 10 Vols. I–IV (Aeronautical Telecommunications)
- ICAO Doc 7488 (Standard Atmosphere)
- ICAO documents available via https://store.icao.int
Specifications
- ASTM D910 (Avgas) and ASTM D7547 (unleaded avgas) — https://www.astm.org
- ETSO-C62 (Aircraft Tyres) — https://www.easa.europa.eu/en/document-library/etso
Geomagnetic data
- NOAA World Magnetic Model (current variation by location) — https://www.ncei.noaa.gov/products/world-magnetic-model
For PPL practice
- AFM / POH of your training aircraft — the authoritative source for limitations, systems and procedures. Always consult first.