被动形式是: be referred
You may refer to your notes if you want.

如果需要be refer to和refer to，可以查阅笔记。

Writers often refer to a dictionary.

作家时常参考字典。

That remark does not refer to her.

那句话不是指她说的。

Study this example and refer to the explanation below.

研究这个例子并参考下面的解释。

refer 的被动形式是 be referred