Relativism: The problem for the Faith Today
Biblical Interpretation in Crisis
Aside from the link to Pope Benedict XVI on the Vatican website, the following links contain mostly free online articles or speeches made by Cardinal Ratzinger when he was still a Cardinal. Ratzinger was prefect of the congregation for the Doctrine of the Faith (CDF) from 1981 until 2005, when he was elected pope.
Catholic Books - Theology and Spirituality