CH 1978 Stamp Day Thun BE, cover cancelled 1.-3.12.78 3612 Steffisburg Dorf, imprint 90 Y.Phil. Lausanne

Switzerland 1978 Stamp Day Thun BE,
official cover "Tag der Briefmarke - Di dalla Marca postala - Journée du Timbre - Giornata del Francobollo - Thun 1978 -
picture of SIMMENTALPOST 1873 (Postkutsche, PTT Museum Bern, CH. Humbert), Offizielle Ausgabe VSPhV / USFS / USPhS",
with add-on cancellation: "1. Briefmarken-Ausstellung - Stufe III - BERNOBA - 1.-3. Dez. 1978 - Steffisburg / Thun",
with imprint: "90ème anniversaire - Societé Lausannoise de Timbrologie - 1888-1978",
without address, cancelled "1.-3.12.78 3612 Steffisburg Dorf - Tag der Briefmarke Thun", luxury conservation.