The bibtex entries that you download from researchr may contain non-ASCII characters, such as with the authors of the following paper:
@article{SchurrD05, title = {Introductory paper}, author = {Andy Schürr and Heiko Dörr}, year = {2005}, doi = {http://dx.doi.org/10.1007/s10270-004-0069-7}, journal = {Software and Systems Modeling}, volume = {4}, number = {2}, pages = {109-111}, }
To use such entries in your LaTeX document, use the inputenc.sty package as follows:
\usepackage[utf8]{inputenc}