If you're using yarn that comes in a twisted hank and don't have a ball winder and swift, check out our easy guide on how to wind a center pull bar by hand.
Nostepinne Tutorial – Cynthia Wood Spinner
Knit Picks' Podcast: Episode 350 - Why are you spitting on your yarn?
Sapphires-n-Purls: A Knitting Blog: Wind a Center Pull Ball of Yarn by Hand
How to wind a skein of yarn into a ball (with no equipment)
Winding Yarn for knitting Winding Yarn with a Swift, Ball Winder or by Hand Stitch Clinic
About yarn - Cheryl Brunette
How to Wind a Center-Pull Ball of Yarn With Your Hands or Swift - Expression Fiber Arts
8 Crochet Tools You Don't Need to Buy — BuddyRumi Amigurumi
How to hand wind a center-pull ball of yarn — BuddyRumi Amigurumi Crochet Patterns