All about ceramic resonators app note from Abracon. Link here (PDF) Why Ceramic Resonators? Ceramic resonators stand between quartz crystals and LC/RC oscillators in regard to accuracy. They offer low cost and high reliability timing devices with improved start-up time to quartz crystals.
App note from Abracon Corporation on quartz crystal oscillators. Link here (PDF)
App note from Abracon Corporation about choosing the right crystal for you application. Link here (PDF)