World Nominal Oil Price Chronology: 1970-2006

Sometimes my memory fails. Today I wanted to know which month in 1973 the OPEC producers started cranking up the price of oil.
To the link-vault, Robin!

I'll explain my purpose next week. For now, your tax dollars at work (worth it, I think).
From the Energy Information Administration:
(click the chart for a spreadsheet of prices,
the link above for the full chart and notes)

My query was answered:

4. Oil embargo begins (October 19-20, 1973)

5. OPEC freezes posted prices; US begins mandatory oil allocation

6. Oil embargo ends (March 18, 1974)

World Nominal Oil Price Chronology: 1970-2006

Here's a hint to what I was thinking.