=TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM")&"-W"&RIGHT(A1,2)-INT((DATE(LEFT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),4),RIGHT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),2),4)-DATE(YEAR(DATE(LEFT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),4),RIGHT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),2),4)-WEEKDAY(DATE(LEFT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),4),RIGHT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),2),4)-1)+4),1,3)+WEEKDAY(DATE(YEAR(DATE(LEFT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),4),RIGHT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),2),4)-WEEKDAY(DATE(LEFT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),4),RIGHT(TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM"),2),4)-1)+4),1,3))+5)/7)+1
=TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM")
=B1&"-W"&RIGHT(A1,2)-INT((DATE(LEFT(B1,4),RIGHT(B1,2),4)-DATE(YEAR(DATE(LEFT(B1,4),RIGHT(B1,2),4)-WEEKDAY(DATE(LEFT(B1,4),RIGHT(B1,2),4)-1)+4),1,3)+WEEKDAY(DATE(YEAR(DATE(LEFT(B1,4),RIGHT(B1,2),4)-WEEKDAY(DATE(LEFT(B1,4),RIGHT(B1,2),4)-1)+4),1,3))+5)/7)+1
=TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM")
=DATE(YEAR(DATE(LEFT(B1,4),RIGHT(B1,2),4)-WEEKDAY(DATE(LEFT(B1,4),RIGHT(B1,2),4)-1)+4),1,3)
=TEXT(DATE(LEFT(A1,4),1,1)-WEEKDAY(DATE(LEFT(A1,4),1,1)-1)+7*(RIGHT(A1,2)-INT((8-WEEKDAY(DATE(LEFT(A1,4),1,1),2))/4))+4,"YYYY-MM")