Iím getting confused with xpath date comparisons, I want to return all values where a @Publication_x0020_Date occurs this month, the below comparison returns all publications only on todayís date rather than this month. I need the date to remain dynamic as I would prefer this to automatically update on a monthly basis.

[number(translate(substring-before(@Publication_x0020_Date,'T'),'-','')) = number(translate(substring-before($Today,'T'),'-',''))]
Iím using Sharepoint Designer, this is a filter criteria for a standard aspx form.

Any help appreciated.