biennial
preferred label: دو سال یکبار @fa
type: Concept
related: triennial

triennial
alternative label: CADA 3 AÑOS
related: annual
related: biennial
broader: periodicity
preferred label: سه سال یکبار @fa
type: Concept

annual
preferred label: سالیانه @fa
type: Concept
related: triennial

periodicity
preferred label: تناوب @fa
type: Concept
narrower: triennial