Gold mine meaning they can get them for cheap price and sell them later on for massive money as I said. They did it with Marković, they'll do it with Živković and probably Jović as well. Not sure about Šaponjić though. He scored some goals for Benfica B, but I don't think he has enough quality to succeed there. They also made a lot of money for Matić, but he arrived from Chelsea. Yet another Serb that did well for them. Đuričić and Sulejmani were average. Others were signed for their B team. It's much easier to sign good prospect from Serbia than, say, Croatia. They love our kids, good investments.