Before revision: Hankinson's equation (also know as Hankinson's formula or Hankinson's criterion) Hankinson, R. L., 1921, Investigation of crushing strength of spruce at varying angles of grain, Air Force Information Circular No.
After revision: Hankinson's equation (also called Hankinson's formula or Hankinson's criterion) Hankinson, R. L., 1921, Investigation of crushing strength of spruce at varying angles of grain, Air Force Information Circular No.