Find the researcher's notes in the Vondel Zoo veterinary office.
You will need a key to the Veterinary Office to access the notes, without it you will not be able to get into this room where the notes is kept.
Place the researcher's notes on the 2nd floor of the church near the castle in the same deployment.
You will find the stairs to the second floor (attic) inside the main entrance.
Take the false notes from the church and place them in the veterinary's office in the same deployment.
You just need to go back to the Veterinary Office and leave the fake notes where you took the original notes in the first task.