(The complete list of official sources used in this work is included in Federico G. and Tena-Junguito, A. 2016b).

CIA (Central Intelligence Agency): The World Fact Book. Country comparison area: https://www.cia.gov/library/publications/resources/the-world-factbook/rankorder/2147rank.html

LEAGUE OF NATIONS (several years) Statistical Yearbook of the League of Nations. Economic intelligence unit, Geneve.

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MACGREGOR. JOHN (1849): Commercial Tariffs and Regulations, Resources and Trade of the Several States of Europe and America. Together with the Commercial Treaties between England and Foreign Countries, Part XXIII. Appendices to the Commercial Reports.

MACGREGOR, JOHN (1850): Vol. I –V. Commercial Statistics. A Digest of the Productive Resources, Commercial Legislation, Customs Tariffs, Navigation, Port and Quarantine Laws and Charges, Shipping, Imports and Exports, and the Monies, Weights, and Measures of all Nations, Including all British Commercial Treaties with Foreign States. Collected from authentic records and consolidated with especial reference to British and foreign products, trade and navigation. Second edition in five volumes. London:Whittaker and Co.

SAUERBECK, A. (1886, 1899, 1908, 1914, 1929, 1939): «Prices of commodities and the precious metals 1846-1885». Journal of the Statistical Society of London 49, pp. 581-648 then «Price of commodities in 1898», ibid, vol. 62 (1899) pp.179-193, then «Price of commodities in 1907», ibid, vol. 71 (1908) pp.132-146, then «Price of commodities in 1913», ibid, vol. 77 (1914) pp. 556-570, then «Wholesale price of commodities in 1928», ibid vol 92 (1929) pp.239-255, then «Wholesale price of commodities in 1938», ibid, vol. 102 (1939) pp.267-284.

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UNITED KINGDOM (foreign countries). Abstract of Reports of Trade of Various Countries and Places for the year 1854. Board of Trade. Through the Foreign Office Foreign from her Magesty´s minister and consul; later, Statistical Tables Relating Foreign Countries (several years): Compiled chiefly from the official returns of the respective countries. British Parliamentary Papers. London; later Statistical Abstract for the Principal and other Foreign Countries in each year from 1907 to 1918. Statistical Department, Board of Trade (UK): Eyre and Spottiswoode, Ltd., East Harding Street, E.C., London.

UNITED KINGDOM (ad annum): Statistical Abstract for the United Kingdom. Board of Trade. London, HM Stationery office.

UNITED KINGDOM (1841-1852): Tables Shewing the Trade of the United Kingdom with Different Foreign Countries and British Possessions. Compiled from Official Returns. Presented to both House of Parliament for Command of her Majestic.

UNITED KINGDOM (ad annum): 1853- 1938, Annual Statement of the Trade of the United Kingdom with Foreign Countries and British Possessions. Compiled in the Statistical Office of the Customs and Excise Department.

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