Name the sales person who helped Elizabeth A. White to purchase Road-250 Black, 48.
name of the sales person = FirstName, MiddleInitial, LastName; 'Road-250 Black, 48' is name of product;
SELECT DISTINCT T3.FirstName, T3.MiddleInitial, T3.LastName FROM Products AS T1 INNER JOIN Sales AS T2 ON T1.ProductID = T2.ProductID INNER JOIN Employees AS T3 ON T2.SalesPersonID = T3.EmployeeID INNER JOIN Customers AS T4 ON T2.CustomerID = T4.CustomerID WHERE T4.MiddleInitial = 'A' AND T4.LastName = 'White' AND T1.Name = 'Road-250 Black, 48' AND T4.FirstName = 'Elizabeth'