config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

    config.Routes.MapHttpRoute(
            name: "FindDetailsByCountry",
            routeTemplate: "api/{controller}/FindDetailsByCountry/{country}",
            defaults: new { country = RouteParameter.Optional },
            constraints: new { country = @"^[a-z]+$" }
        );

constraints: new { country = @"^[a-z]+$" }

constraints: new { country = @"^[a-z]s+$" }