Cook Islands 5 Dollars Centenary of the sinking of the Titanic series

Hello,

I am trying to find out more information on Cook Islands 5 Dollars Centenary of the sinking of the Titanic series so it can be added to the catalogue. I tried searching online to find a reliable resource and cannot find one. They are the "normal" ones of this:

https://en.numista.com/catalogue/pieces139005.html

I have the following of the series in my collection:
Cook Islands 5 Dollars Centenary of the sinking of the Titanic series : Second Class
Cook Islands 5 Dollars Centenary of the sinking of the Titanic series: Band Playing
Cook Islands 5 Dollars Centenary of the sinking of the Titanic series: Shocking News
Cook Islands 5 Dollars Centenary of the sinking of the Titanic series: Atlantic Crossing
Cook Islands 5 Dollars Centenary of the sinking of the Titanic series: Maiden Voyage
Cook Islands 5 Dollars Centenary of the sinking of the Titanic series: Final Moments
Cook Islands 5 Dollars Centenary of the sinking of the Titanic series: Abandon Ship
Cook Islands 5 Dollars Centenary of the sinking of the Titanic series: Carpathia Rescue

I am wondering where would be a good place to get information on the metal they are made of and mintage figures from thanks.