code: func (db *Database) FindRef(ref *DBRef) *Query {
  	var c *Collection
  	if ref.Database == "" {
  		c = db.C(ref.Collection)
  	} else {
  		c = db.Session.DB(ref.Database).C(ref.Collection)
  	}
  	return c.FindId(ref.Id)
  }
docs: // NOTE: Order of fields for DBRef above does matter, per documentation.
  // FindRef returns a query that looks for the document in the provided
  // reference. If the reference includes the DB field, the document will
  // be retrieved from the respective database.
  //
  // See also the DBRef type and the FindRef method on Session.
  //
  // Relevant documentation:
  //
  //     http://www.mongodb.org/display/DOCS/Database+References
  //