In 1927, Konrad Schünemann summarized these older views and proposed the origin in a Slavic stem "strěg" ("custodia", guard). This theory was later extended by Ján Stanislav who also explained the origin of the initial vowel missing in Latin and later Czech sources ("Střehom"). The introduction of a vowel before the initial consonant group is a regular change in the Hungarian language ("Stephan" → "István", "strecha" → "esztercha"), but the initial ""O"" in later Slavic forms can be explained by an independent change–an incorrect decomposition of the Slavic prepositional form. Both authors noticed the high number of Slavic placenames in the region (Vyšegrad, Pleš, Kokot, Drug, Komárno, Toplica, etc.) and similar Slavic names in other countries (Strzegom, Střehom, Stregowa, etc.). Both authors believed that the stem "strěg" was a part of the Slavic personal name, but Šimon Ondruš suggests a straightforward etymology. The Proto-Slavic – to watch, to guard, present participle "stregom", "strägom" – a guard post. The later Slavic form was created by an incorrect decomposition as follows: "vъ Strägome" (in Strägom) → "vo Strägome" → "v Osträgome" like Slovak "Bdokovce" → "Obdokovce", "Psolovce" → "Obsolovce".