When searching any of the WU catalogs, MOBIUS, and WorldCat, you don't need the diacritic marker but can include if you wish to.
For example, searching "étude" or "etude" will both bring up results for "étude". But the German eszet ß should be changed to "ss". For example, "muß" should be searched for as "muss".
You also don't need diacritics but can include them when searching most of the Libraries databases, such as Academic Search Complete. Some databases do require them.
