Original source for a quote by Lobachevsky Lobachevsky is quoted in many places to have once written (said?) "There is no branch of mathematics, no matter how abstract, which may not someday be applied to phenomena of the real world." (In the original: Нет ни одной области математики, как бы абстрактна она ни была, которая когда-нибудь не окажется применимой к явлениям действительного мира.) My question is: where can this be found in his work? I am not interested in being told about a book from the 1980s that has this in a list of quotes, so please don't waste time telling me about sources other than Lobachevsky's. 
I did find online a copy of some of his collected works, but the file wasn't in a form that allowed a text search by computer.
 A: The list of reference numbers for the site linked by Marcus Barnes is here.  This gives us the reference:
-115. Зенкевич И. Г. Не интегралом единым. Тула, 1971. 136 с.
It appears to be a collection of quotes, and according to this site, it has a list of original references at the back.
A: OK.  I was curious about this too.  Some sleuthing on my part using Google Translate has provided a hint.  I found this page:  
http://matematiku.ru/index.php?option=com_content&task=view&id=296&Itemid=2
It cites Lobachevskii's collected works: "op. at 115, section 117".  His collected works were edited by V. F. Kagan.  Kagan also wrote a book: "N. Lobachevsky and his contribution to science."  We need to verify this citation, but I don't have direct access to Lobachevsky's collected works. 
Anyway, let's hope this hint allows up to nail down the exact citation for this wonderful quote.
Clarification: My suspicion is that the citation is referring to Lobachevskii's collected works.  The "op." usually refers to "opus", that is, an authors' (edited) collected works.  To verify the citation, we will need to check Lobachevsky's collected works, which were edited by V. F. Kagan.  Unfortunately, I do not have access to a copy at this time.
