Help with creating a IF statement

I am a novice at best in excel and need some help. I am trying to make a if statement that references a specific cell on another sheet in a workbook so that if that cell has "Estimate" typed into it then and "E" appears in a cell on a summary sheet. So far I have this =IF('136'!$E$17="Estimate",E). All the examples I can find have less complicated formulas and they have an if, then....=IF(A1="Estimate",E,A) I want the cell to be left blank if the reference cell does not have "Estimate" in it so my thought was just don't put anything other than the "E". I am such a novice here I don't even know if I'm explaining this adequately.