@@ -19,4 +19,6 @@ exports.Date = require('./date');
 
 exports.ObjectId = require('./objectid');
 
+exports.ObjectId = require('./dbref');
+
 exports.Mixed = require('./mixed');

/**
 * Module exports.
 */

exports.String = require('./string');

exports.Number = require('./number');

exports.Boolean = require('./boolean');

exports.DocumentArray = require('./documentarray');

exports.Array = require('./array');

exports.Buffer = require('./buffer');

exports.Date = require('./date');

exports.ObjectId = require('./objectid');

exports.Mixed = require('./mixed');

Should be `exports.DBRef` i guess.