List down the customers that purchased the product named Xerox 23 in the South region.
product named Xerox 23 refers to "Product Name" = 'Xerox 23'; customers refers to "Customer Name"
SELECT DISTINCT T2.`Customer Name` FROM south_superstore AS T1 INNER JOIN people AS T2 ON T1.`Customer ID` = T2.`Customer ID` INNER JOIN product AS T3 ON T3.`Product ID` = T1.`Product ID` WHERE T1.Region = 'South' AND T3.`Product Name` = 'Xerox 23'