76/ 721 Zwart, P. [N.K.F.]. "50 kV 1-aderig (...) Geen ionisatie in bedrijf (...)". Advertisement, (1927), 31,8x10,7 cm. (leaf), letterpress text, on cut out right half of a leaf from a periodical (Sterkstroom/ Tijdschrift voor Electrotechniek?), numb. "A4" in right upper corner, (incomplete) other adverts on verso.

- Dated "19.10.27" in pencil on verso. = Cf. PZ-118 (proof).