Another Rad Ref librarian found a website on Iranian anarchism from znet:interview with Payman Piedar, the editor of Nakhdar, a Farsi/English-language anarchist-communist magazine(2005).
Another site mentions the names of Kacha and Mares in relation to Kafka, others include a general Czech anarchist history and an ANARCHOPEDIA article on the Czech Republic
Google Scholar only gets 2 hits for: "Michal Mares" "Michal Kacha", and I would plow pretty thoroughly through the "30 hits" (14 unique ones) that a regular Google web seach gets gets. Even the ones in foreign languages might give names and places that could be leads (even try www.google.cz, if you want to try guessing at some Czech language ones). The same search gets 3 hits in Google Books and I would go with the broader search: michal mares kachka (5 books). All 5 are restricted books (under copyright), but Open Worldcat will let you search their titles, to find the libraries nearest to your computer or network provider that own them.
I tried our commercial databases, JSTOR, Project Muse, Historical Abstracts, Arts & Humanities Citation Index, New York Times Historical, and Proquest Dissertations; but get nothing related to these people - even with a very broad search: mares and kacha. The only lead is in Arts and Humanities Citation Index 1996-present and Social Sciences Citation Index 1956-present, which gets a few cryptic references to mares m, such as MARES M DIAIRES F KAFKA 1910 (repr 1964) p233, which was cited by Lowy M in "'Theologia negativa' and 'utopia negativa': Franz Kafka" Source: FILOSOFICKY CASOPIS v49 n1 pp 27-51 2001.
So if you are up for a tough grind through many journal articles, to get sketchy leads back to Mares, Web Of Science (Arts and Humanities and Soc Sci sections) is worth a try. Arts and Humanities Search (Firstsearch) will take you back to 1980, but I only get 5 hits for cited author phrase=mares m*, and only about 1 or 2 seem to be THIS Michal Mares. The trouble with ISI indexes is that , even limiting to A&H and Soc Sciences, you still get many Mares M hits which turns out to be for a VERY different Mares M. And I get no references to kacha m in the citation indexes. I double checked Lexis Academic, in case recent articles might have mentioned these (mid 20th century?) figures. But the search: michal mares and anarch! in all sources all dates gets 4 hits, and only the first one, a German article, seems to have anything on Michal Mares: Wäre K. heute Fan von Sparta Prag? Frankfurter Allgemeine Zeitung, 20. Oktober 2001, Feuilleton; S. 45, 816 words.
Google Books and Amazon.com may well be your least difficult starting points on this, unless you get very lucky in old print indexes and bibliographies of books and journals that have yet not made it into Google Books. I would still start with those Google Books and Amazon.com references, to get a foot in the door.
The history of Iranian anarchists may be an even more formidable challenge in the commercial, academic library databases. JSTOR gets 460 hits for: iran and anarchist*, including "Strengths and Weaknesses of Iran's Populist Alliance: A Class Analysis of the Constitutional Revolution of 1905-1911". John Foran. Theory and Society, Vol. 20, No. 6 (Dec., 1991), pp. 795-823. On pp. 812-813, referring to the 2nd Majlis 1909-1911, it talks about the Moderate Party "...defending society against the terrorism of the anarchists..."; and "The Crowd in Iranian Politics 1905-1953" E. Abrahamian. Past and Present No. 41 (Dec., 1968), pp. 184-210 which talks about "...demonstrations...belonging to the 'anarchistic' past."
Unfortunately, JSTOR does not let you specify that both words MUST appear even on the same page, so you would have to plow through 10-15 pages in each of the 460 hits. It is significant, however, that limiting to title or to abstract gets zero hits – even if you do a very broad search: iran* and anarch*. My guess is that there is very little on actual Iranian anarchism in JSTOR, and that database is probably our biggest full-text source that would be a reasonable place to try this search.