Most exams are open book. Examination information, including whether your exam is open- or closed-book, can be found in the applicable exam information by searching for your exam in the exam catalog.
If you are taking a Contractor/Trades exam, examination information will be found in the applicable bulletin found in the exam catalog.
Exams that are open book will appear as below:
Note that different open book exams may have different requirements for what references are allowed. The information regarding the open book policy can be found under the references section. One example is included below (note, this is an example and this policy is not applicable to all exams).