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《集邮博览》第3期的一篇文章提出了一个很有意思的问题:如何区分邮资明信片式门票的正面和背面?其实不仅仅是门票,其他加印的邮资明信片以及钱币等,也有正面和背面的问题。
An essay in Issue 3 of Philately presented an interesting question: How to distinguish the front and back of postage postcard tickets? Not just tickets, other printed postcards and coins, but also front and back The problem.