Exclude lines if ref and grade match in another sheets

Question

It is the first time I am using Google sheet and I need to sort tables from two differents sheets. I want to keep only the ref that don't have a grade of A

here is a link in google sheet https://docs.google.com/spreadsheets/d/1quXkNuSYPF7MCs7_PGzjHKOLDf0TSvPqlEumNCWc0lc/edit?usp=sharing

February '22

March '22

Expected result (comparison between Feb and March)

Thanks for helping

Answer 1

try:

=QUERY({'February''22'!A:B; 'March''22'!A2:B}; 
 "where Col2 <> 'A' and Col2 is not null"; 1)

or if you want only uniques:

=UNIQUE(QUERY({'February''22'!A:B; 'March''22'!A2:B}; 
 "where Col2 <> 'A' and Col2 is not null"; 1))