Quorum requirements for a referendum to be valid

Paraguay
Answer
No quorum requirements
Source
Electoral Code (Código Electoral Paraguayo – Ley No 834-96)
http://www.oas.org/es/sap/deco/moe/Paraguay2013/docs/CODIGO_ELECTORAL.pdf
Paraguay'sConstitution of 1992 with Amendments through 2011
https://www.constituteproject.org/constitution/Paraguay_2011