Related Clues:

• Cartoons collected in 'Cows of Our Planet'
• Comic collected in "Cows of Our Planet"
• Cartoon in which one cow says to another 'Hey, wait a minute! This is grass! We've been eating grass!'
• Gary Larson cartoon [third word of ''start'']
• Gary Larson comic with cows (In this answer, note letters 4-8)