C++0x variadic template pass by reference

I want to use variadic template feature for my application but I don't want the objects to be passed by value (as objects are quite complex in my case). I want to pass them by reference (not as pointers).

void func()
{
}

template<typename Function1, typename... FurtherFunctions>
void func(Function1 f1, FurtherFunctions... further_functions)
{
    // doing some processing here...
}

How could I pass the arguments by reference and ensure that they are not copied?