Commodity market in Sumer between 4500 BC and 4000 BC. Sumerians first used clay tokens sealed in a clay vessel, then clay writing tablets to represent the amount—for example, the number of goats, to be delivered. These promises of time and date of delivery resemble futures contract. Early civilizations variously used pigs, rare seashells, or other items as commodity money. Since that time traders have sought ways to simplify and standardize trade contracts. Gold and silver markets evolved in classical civilizations. At first the precious metals were valued for their beauty and intrinsic worth and were associated with royalty. In time, they
The Aurum Film Encyclopedia through 1990 and a different set of appendices. Ten pages were added to the new edition, covering the few films produced during the years 1984 - 1990. This edition was reprinted in 1995. Published in 1984, "The Aurum Film Encyclopedia: Science Fiction", followed the history of the genre chronologically, from 1897 – 1983. Unlike the previous volume, silent genre titles are included, and even minor genre films are reviewed in the main text. Also unlike the first volume, Hardy mentions the names of the various critics who provided the reviews in the text, which in this book were Denis Gifford,