Kyle Shanahan recaps first day of 49ers practice in Colorado - Sactown Sports
49er-Giants recap: Levi's Stadium still has grass/turf issues - Niners Nation
49ers' George Kittle calls for surface continuity among NFL stadiums, done dealing with 'crappy turf'
49ers' Deebo Samuel a 'firm believer' in grass over turf in NFL
Inside the NFL turf debate: Injuries, safety measures, problems - ESPN
Ask Farmer: Do players prefer grass or turf?
Led by George Kittle and stout defense, 49ers bully Cowboys to stay unbeaten
Levi's Stadium, America's Most Tech-Savvy, Can't Grow Proper Grass
49ers sparkling new Levi's Stadium sees field fail, new grass goes in – The Mercury News