According to [Using Subqueries](https://docs.oracle.com/database/121/SQLRF/queries007.htm) Oracle SQL accepts a subquery in the from-clause of a select statement, like

```
SELECT * FROM ( SELECT a FROM b );

```

However, looking at the [SELECT documentation](https://docs.oracle.com/database/121/SQLRF/statements_10002.htm), I see no possibility to get to select/subquery in the from clause (e.g. from the rules `table_reference` or `join_clause`).

Am I missing something here, is this part of the SQL grammar documented elsewhere? Or is this another incomplete part of the documentation?