In wikipedia (https://en.wikipedia.org/wiki/Cyclostationary_process) one can find the definition of a wide sense cyclostationary process as 
the stohastic process in which
$$E[X(t)] = E[X(t+T_0)] ,\forall t$$
$$R_x(t,\tau) = R_x(t+T_0,\tau) ,\forall t,\tau$$

Then, because $R_x$ is periodic it can be expanded in Fourier Series as 
$$R_x(t,\tau)= \sum_{n = -\infty}^{\infty} R_x^{n/T_0}(\tau)\cdot e^{i2\pi \cdot n/T_0 \cdot t}$$
In the last sentence (in wikipedia) it says:
"**Wide-sense stationary processes are a special case of cyclostationary processes with only $ R_{x}^{0}(\tau )\neq 0$."**

But if that is true, I can conclude that 
$$R_x(t,\tau)= R_x^{0}(\tau) = 1/T_0 \int_{-T_0/2}^{T_0/2} R_x(t,\tau) dt$$

I suspect an error here. If anyone could say anything useful what maybe the writer wanted to say about it, I would be grateful. Thanks in advance