Higgins & Gage World Postal Stationery Catalog is the reference you need to identify postal stationary items. The specific Great Britain aerogrammes you asked about were also listed in the 1959-1960 edition of Sanabria's Airpost Catalog as follows:
Higgins & Gage World Postal Stationery Catalog is the reference you need to identify postal stationary items. The specific Great Britain aerogrammes you asked about were also listed in the 1959-1960 edition of Sanabria's Airpost Catalog as follows:
