77/ 568 Zwart, P. [N.K.F.]. "De doorslagvastheid van onze normaalkabel is abnormaal. De bedrijfszekerheid van onze normaalkabel is enorm". Leaf N160 from the N.K.F. Normalieën (Normalisation) booklet, (1924), 15,9x11,4 cm., recto letterpress text printed in purple and orange, verso letterpress text printed in black.

- Rubbed/ dam. spots in corners from former mounting.

= Rosbeek p.47 and 48; Müller p.100.