The prewar pistols have "Ceska Zbrojovka, Prague" on the top of the slide. Pistols manufactured under German occupation are marked "Bohmische Waffenfabrik, A.G. IN Prag" and the last ditch pistols have the rib ground down and only a serial number near the back sight.
http://www.tague.at/pistolen/en_inde...es/en_cz27.htm
http://www.gunblast.com/RKCampbell_CZ27.htm