Possible Clues:

• Symbol in a Riemann sum
• Greek character drops temperature in part of plant
• ... several of whom repulsed character from Europe
• Bring up a girl, briefly inculcating good character
• Conclusion reached by Aristophanes, Sophocles, and Euripides
• Greek letter used as summation sign
• What it all adds up to in Greek?
• Letter about gas, I�m perplexed
• Father and son writing up about first of Grecians — or his character?
• The 18th letter of the Greek alphabet