Wants to Dramatize Works of Persecuted Russian

Dear Rich: I have written a play in which I use the works of a Russian writer (in my translation)named Daniil Kharms (1905-1942). He wrote very short absurdist works, one-paragraph stories and the like, so I actually include several works in their entirety in the playscript. None of these works were published during his lifetime. (During his lifetime he only published two poems, plus many works for children, none of which I'm using.) I want to send the script for the play around to theaters without any questions about permissions hanging over it. I've looked at the Library of Congress website but question the value of ordering a search for so many short works. Kharms lived and died in Russia. (He died in a Leningrad prison during the siege of Leningrad. A friend hid and preserved his manuscripts.) He had no children; his wife died abroad in the late 1990s or early 2000s. There are various collections of his stories in English translation dating from the 1960s to the 1990s (on the copyright page of which, copyright notice is given for the translations; but not for the originals). There were two different Russian collections of Kharms's stories published in Germany in 1974 and 1978. In Russia itself, most or all of these works were not published until the late 1980s under Gorbachev. There is a "Complete Collected Works" in Russian which came out in 1998. Thanks for introducing us to the work of Mr. Kharms. We've reviewed the copyright notices for a few of the Kharms translations and can confirm that the copyright claims are only made to the translations and that there is no mention of a Kharms copyright or a license from anyone claiming to be the Kharms estate. For example, this copyright page from a British collection (Click Search Inside This Book and choose the copyright page) attributes authorship to Kharms, but that's all, apparently. For these reasons, we believe that currently Kharms' work qualifies as an orphan work, technically protected under U.S. Copyright but not enforced because the owner of rights can not be located. (That would explain the freedom with which translations have appeared.)
U.S. Public Domain. Hang on because things can get complex when analyzing the public domain. Here are few things to consider.

• Unpublished works. On January 1, 2013, all unpublished works (whenever or wherever created) by authors who died in 1942 will fall into the public domain in the U.S. So, anything by Kharms that hasn't been published will be PD. 
• Works Published Before January 1, 1978. The Russian collection of work published in Germany in 1974 would be protected for 95 years under U.S. Copyright provided that it had a valid copyright notice. 
• Works Published After January 1, 1978. The Russian collection of work published in Germany in 1978 receives the same term of copyright as if published in the U.S. -- that is, life of the author plus 70 years. So, that also would be public domain in 2013.

Copyright Office Records. It's quite easy to search the Copyright Office Records and we recommend that you do so (choose to search by name and type in "Kharms Daniil"). Our search seems to confirm that there is no copyright claim by Kharms' successors (assuming he has any). By searching the records, you will see that there have been dramatizations and translations, none of which attribute copyright to Kharms, and none of which claim copyright over the original work (only over the translations and modifications).