What about Ribet's great Inventiones paper from the 70's $\textit{A modular construction of unramified }p\textit{-extensions of }\mathbf{Q}(\mu_p)$A modular construction of unramified $p$-extensions of $\mathbf{Q}(\mu_p)$ ? I think it should be mentioned!
From Ribet's website (pdf) or EuDML