I would like basic references on the fundamental groups $\pi_1(V)$ of ''quadratic'' sub-varieties $V$ in $\mathbb{R} P^{n}$. To clarify what I mean by "quadratic sub-variety" in $\mathbb{R} P^{n}$, I mean the image $V$ by the fibration $p:\mathbb{R}^{n+1}\longrightarrow\mathbb{R} P^{n}$ of any sub-variety $W$ of $\mathbb{R}^{n+1}$ defined merely by a non-degenerate homogeneous polynomial $Q$ of degree 2 in $\mathbb{R}^{n+1}$ such that $\forall x\in W\subset \mathbb{R}^{n+1}$ we have $Q(x_1,\ldots,x_{n+1})=0$, and then $V\equiv p(W)$.
Thanks.