To find a leader to sign, you need to make an appointment with the phone in advance.

In general, what kind of business do you work in, so the leaders involved are basically those who sign frequently, so you know them all. When you go, just say that this is our unit somewhere, please review and reply. Needless to say, you can't go in when you have time and no one talks with others, so you can't go in without a punctual leader in your work. If you can't approve today, you won't be tired when you arrive, but you will get used to knowing it slowly without too many pleasantries.