karbovanets worth of State Treasury Notes (); the sum was increased to 500 million karbovanets on 12 May, which, in its turn, was doubled on 9 July 1918. While Yakiv Zozulya attributes such rapid increases to the agreement with Austria-Hungary and German Empire, whereby Ukraine granted a 200 million karbovanets "unlimited-term loan" to each of these countries, thus interpreting it as a sign of clientelism, Pavlo Hay-Nyzhnyk said the money was needed to revive the country's economy anyway. In essence, State Treasury Notes were 4-year treasury bonds with 3,6% simple interest per annum, paid every six months (on 1 July and 2 January), issued in denominations of 50, 100, 200 and 1,000 hryvnias. They had a unified design prepared by Heorhiy Narbut, with a roughly square centre, where the value of the bond was written, plus four coupons on either side of the note, worth respectively 0.90, 1.80, 3.60 and 18 hryvnias each; the only feature that was different between each of these was colours. Due to the enormous size of the notes, as well as due to the location of coupons, they were nicknamed "airplanes" (). The coupons and the notes were not formally intended to be legal tender in the sense that the possibility to redeem them at banks was limited by the dates in coupons, but in practice, due to an acute shortage of small change, these pieces of paper were readily cut out and circulated as plain currency, and Zozulya reports that even government agencies accepted both the notes and the coupons for payments. The coupons and the State Treasury Notes were thus described as "surrogate banknotes". Shahivky fractional currency Unlike State Credit Notes and State Treasury Notes, shahivky (named so after shah, the subdivision of hryvnia, in which the money was denominated) were postage stamp-sized, and indeed they were sometimes used as postage stamps due to the dearth of "real" postage stamps. There was additionally a strong deficit of metals. Therefore, on 18 April 1918, the government authorised to issue paper "coins" of 1, 2, 4, 6, 10, 20, 30, 40 and 50 shahiv. The first four denominations have never been issued nor are known to have ever been printed. According to various estimates, the other five shahivky accounted for about 24-38 million hryvnia in circulation. Among those issued, the 30 shahiv stamp was rarer than the other denominations. Unlike the postage staps, which were