You may try this with Indirect (supposing "February" is on cell AA1):
=INDEX(INDIRECT(AA1 & "!A1:Z100"),MATCH("USD",INDIRECT(AA1 &
"!A:A"),0),MATCH("AUD",INDIRECT(AA1 & "!4:4"),0))

"Newbie" wrote:

I have the following formula which works fine:

=INDEX(February!A1:Z100,MATCH("USD",February!A:A,0 ),MATCH("AUD",February!4:4,0))

I would like February to be the variable contents of a particular cell but
cant get my referencing right. Can anyone please help??