You cannot write anywhere other the test booklet. If you get caught writing on the reference materials you are bringing there is a high chance that the whole binder will be confiscated.
I am trying to keep the momentum and is in the process of going for another exam either CEM or CPD. Have not decided yet but it kept me off from thinking the PE exam....sometimes.
1. MERM
2, MERM Quick Reference
3. MERM Printed Index
4. Cameron
5,6,7,8 ASHRAE Handbooks
9,10,11 NCEES & PPI Practice Exams
12. PPI Unit Conversions
13 Binder of problems I solved