UNE-EN 60641-3-1
Pressboard and presspaper for electrical purposes - Part 3: Specifications for individual materials - Sheet 1: Requirements for pressboard, types B.0.1, B.0.3, B.2.1, B.2.3, B.3.1, B.3.3, B.4.1, B.4.3, B.5.1, B.5.3 and B.6.1 (Endorsed by AENOR in December of 2008.)