There is some useful links :

• Canadian Machinery Vibration Association
  www.cmva.com
• Impedance - Acoustique & Vibrations
  www.impedance.fr
• Robert B. Randall, School of Mechanical and Manufacturing Engineering
  www.mech.unsw.edu.au/mech/profiles/randall.htm
• Dytran Instruments, Inc.
  Piezoelectric sensors for dynamic measurements
  www.dytran.com
• Conception de Systèmes et Technologie Mécanique
  www.cstm.fr/
• Welcome to Wilcoxon Research Inc.- sensing the future of vibration instrumentation
  http://wilcoxon.com/
• 01bd-Stell, produits et services de diagnostic vibratoire
  www.01db.com/