From: Rooidam
This Prisoner of War record for Gerhardus Jacobus Van Der Heefer was transcribed record from various documents held at the National Archives, South Africa, including arrest and shipping information from newspaper sources like De Zuid-Afrikaan.
https://www.gendatabase.com/boer-war-prisoner-record.php?q=1353&r=Gerhardus Jacobus&s=Van Der Heefer&ref=
This set of Prisoner of War documents can be accessed online via the FamilySearch.org project by Clicking Here.