Please note that within this document, the term "Onayn" refers to one a mourner whose relative is not yet buried. This is only a working definition, but that the actual paramaters of this stage are subject to debate by the commentators.
The first night, whether one is considered a regular Mourner or an Onayn: Rosh Berachot 2:15
Whether aninut at night is a Rabbinic or Biblical Institution: Berachot 16b
Distinction between where the corpse is/isn't before the mourner: Berachot 17b-18a
An Onayn on Shabbat: Berachot 18a, Moed Katan 23b