IF + INDIRECT Excel

I have been trying for hours to get the =IF(INDIRECT... Funktion to work, but i cant get it to work.

Hope you can help me out.

I have 3 worksheets (Calender, sheet1, sheet2 (up to 50))

In Calender I have different "inputs" like Name(A1), City(A2), Number(A3) etc.

On A4 Ii have a booking number. This booking number refers to sheet1 or sheet2

In sheet1 and sheet2 I have the same "inputs"

What I would like to, is when I type sheet1 in Calender on B4 it fills in B1+B2+B3 with the info from sheet1 A1+A2+A3

If i insted used sheet2in Calender!B4, it would fill in the info from sheet2