source tables for VK13

Hi. I need to prepare a transaction which will display price-changes history. Very similar is VK13. I'd like to ask which tables keep data about:

- date of price change

- amount of new price

- type of price

- other info (dates from, to ...)

<b>But the most important thing: WHO (user) set that new price</b>

I'd be very thankful for giving me some advice. Greetings. P.