How to refer to a source with "minor" typos in the title?
Depending on where your sources have been published, the format/style guide you are using, and where you have found them, the definitive way of referring to a source is to cite it using the title as it is written in the source publication. 

In some cases you will find character accents missing as it is not always a trivial matter to write accents - this depends on the character set you are using. I have seen that older papers and articles that were typeset for English publications simply did not have those characters available in the character set used at the time. Thus accents and special characters were "anglicised" - for example, château as chateau, leçon as lecon, etc.