The last name or xxx, which yields cases where the family name is missing, of at least one spouse must be specified. xxx as a first name yields cases where the first name is missing.
You can use wildcards in a name or a firstname. '%' operator matches any string of zero or more characters. It can be used as either a prefix or a suffix. (ex: 'goudr%') '_' (underscore) matches any single character in a string comparison operation that involves pattern matching. (ex: '_an')
You can limit your research on the basis of a period of marriage.