They are always written, because by writing down a Constitution you 'fix' its provisions. After that, a Constitution always is very hard to change or make Amendments to. And that makes it rigid.
Edward Washington Suppiger has written: 'An analysis of the motion of a rigid body' -- subject(s): Dynamics, Rigid, Rigid Dynamics
John Prescott has written: 'Mechanics of particles and rigid bodies, by John Prescott' -- subject(s): Dynamics of a particle, Dynamics, Rigid, Mechanics, Rigid Dynamics
Jens Wittenburg has written: 'Dynamics of multibody systems' -- subject(s): Rigid Dynamics 'Dynamics of systems of rigid bodies' -- subject(s): Rigid Dynamics
Itself
written and unwritten, codified and uncodified flexible and rigid
Vladimir Kitaev has written: 'Rigid rod polymers in confined geometries'
Dietrich Koch has written: 'Characterisation of the regeneration performance of rigid ceramic filters'
J. R. Pounder has written: 'On relativistically rigid surfaces of revolution'
W J. Louden has written: 'An elementary Treatise on Rigid Dynamics'
Joannes Terheijden has written: 'Syntheses and structural aspects of rigid arylplatinum complexes'
James R. Pounder has written: 'On relativistically rigid surfaces of revolution'
S.W Ekanayake has written: 'Rigid and pin jointed plane frame analysis'