During compiling literature using BibTeX I've got the following message in the log file:
This is pdfTeX, Version 3.1415926-1.40.10 (MiKTeX 2.8)
(preloaded format=pdftex 010.12.7) 7 DEC 2010 00:33 entering extended mode
Missing character: There is no ę in font cmr10!
What should I do to fix this problem?