Some of my tests
?DatePart("ww", #12/25/2016#, vbSunday, vbFirstFourDays)
52
?DatePart("ww", #12/25/2016#, vbSunday,vbFirstFullWeek)
52
?DatePart("ww", #12/25/2016#, vbSunday, vbjan1)
53
?DatePart("ww", #12/27/2015#, vbSunday, vbjan1)
53
?DatePart("ww", #12/25/2016#...