What shapes a country's bibliographic history is a complex of political, economic and historic events. What is provided here is just a brief discussion of some of the factors a scholar should keep in mind when looking for resources.
All of the above are factors that will affect research in this region no matter which country is your focus. The first is the most obvious and most scholars are aware that censorship was a major factor in particular areas of the region. It is important to keep in mind that it will affect what is available for certain time periods and in which languages. It also affects the types of sources that list materials. So, for example, the Soviets published Svodnyi Katalog Russkoi Nelegal'noi i Zapreshchennoi Pechati XIX Veka in 1977 making accessible all the titles of the 19th century that had been censored or suppressed.
Censorship was one of the motivating factors in the passage of depository laws. These laws required that some number of copies would be "deposited" with the censors or in a designated repository, usually the national library. The effect is an extremely comprehensive collection in those institutions designated as depository institutions. It is, therefore, extremely useful to know which institutions were depositories when trying to do a comprehensive literature search.
Censorship functioned in many ways. Along with the foreign domination it sometimes served to inflame national pride in the intellectual history of a country. It also raised the fear that a nation's intellectual history would be lost without someone keeping a careful record. Thus in Poland it was one of the factors that led to Estreicher's compilation of his monumental Bibliografia Polska.
Domination by a foreign power also meant, in some cases, that publications of a nation were deposited in the libraries of the conquering nation. Certainly, the Austrian National Library has an excellent Czech collection from the period during which the Austro-Hungarian empire dominated the region. The scholar who is aware of this history can make the broadest use of all the resources available. The Austrian National Library Catalog is available online and can provide an alternate source for obtaining copies of material from the 19th century. There are many such examples. It was also the case for the Russian Empire that much of their publishing output was deposited in the national collections of the regions they dominated. Thus, Helsinki University's Library is a major resource for scholars of the Russian Imperial period. This is not to suggest that these collections replace the national collections of the region of interest, but that broaden the scholarly options avaialble.
Some countries have a history of creating very elaborate bibliographic tools, facilitating research. Others have not focused on the production of such resources and have emphasized generalized resources for research such as national bibliographies, encyclopedias, etc. This has been the case with the Czech Republic in the past. So for example, when seeking information on Czech periodical publications one would use the Czech encyclopedia as there was no comprehensive Czech source that described in detail their periodical publications. Interestingly, their digital tools are very elaborate and provide the scholar with an array of resources for research.
The Russians, Ukrainians, Hungarians, Bulgarians, and the Poles have a complex system of bibliographic resources. The Hungarians, Czechs and the former Yugoslav republics have emphasized the more generalized resources in their print resources. They have developed some remarkable resources in electronic format. Some of these tools are very valuable for a variety of regional specialties.
The Czech National Library Portal of catalogs is an example of such a resource. This portal http://www.nkp.cz/pages/page.php3?page=sluz_altnk_onlinekat.htm will allow you to search their current catalog of course. But it is also an access point for the catalog of the Slovanská Knihovna -- a very important collection of Russian materials.
The Hungarians have their entire retrospective national bibliography available which includes a wealth of biographical information, all online at http://mnb.oszk.hu/.
Similarly, the scanned card catalog of the Jagiellonian Library provides access to what was a depository collection for the Imperial Russian government in the years of Russian control of the region.[To see an example try searching the term “izvestija” in Jagiellonian’s card catalog)
Paper and digital sources have been merging in recent years most notably in the Internet Archive, European Library and GoogleBooks. With the advent of these large repositories of digital materials the traditional medium is often ignored. However it should be kept in mind that many of the digital media are in a less than optimum form and may be more difficult to use online than in paper. A good example is the scanned version of Smits' Half a Century of Soviet Serials. While this can be an invaluable source to have available for research the digital copy is somewhat cumbersome as it is not a truly searchable edition. This is also the case for the many scanned card catalogs.