1883, Clarence E. Dutton, Fourth Annual report of the United States Geological Survey:The second form of the lavas is called by the natives a-a, and its contrast with pahoehoe is about the greatest imaginable. It consists mainly of clinkers sometimes detached, sometimes partially agglutinated together with a bristling array of sharp, jagged, angular fragments.
1999, A. Ganeri: Violent Volcanoes:A'a is thick, sticky lava which forms jagged, chunky rock when it cools.
2004, Richard Fortey, The Earth, Folio Society 2011, page 44:I overheard a geologist say that a good pair of boots can be rasped to bits on a‘a in a couple of months.
