Please list the website purchasing links of the vendors from whom the product Hex Nut 5 can be purchased.
website purchasing link refers to PurchasingWebServiceURL
SELECT T3.PurchasingWebServiceURL FROM ProductVendor AS T1 INNER JOIN Product AS T2 ON T1.ProductID = T2.ProductID INNER JOIN Vendor AS T3 ON T1.BusinessEntityID = T3.BusinessEntityID WHERE T2.Name = 'Hex Nut 5'