Methods of testing soils for engineering purposes, Method 3.2.1: Soil classification tests - Determination of the plastic limit of a soil - Standard method
High-voltage switchgear and controlgear, Part 200: AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV (IEC 62271-200:2011/COR1:2015, MOD)