https://ideas.repec.org/a/ecm/emetrp/v61y1993i1p248-49.html
Erratum [The Great Crash, the Oil Price Shock and the Unit Root Hypothesis]
Downloadable (with restrictions)! The unit root hypothesis is examined allowing a possible one-time change in the level or in the slope of the trend function....
the great crashoil price shockunit rooterratum