Crochet: How to Crochet a Cord which uses two separate strands at the same time - YouTube
Two at a Time- Double Up that Yarn - Linda Dean CrochetLinda Dean Crochet
How to Crochet with Multiple Strands of Yarn - the neon tea party
Guide to Multi-Strand Crochet -- Double-stranded or multi-stranded crochet, where you hold two or more yarn strands… | Crochet throw blanket, Crochet, Crochet throw