Category Theory in Context by Emily Riehl (https://emilyriehl.github.io/files/context.pdf)
Basic Category Theory by Tom Leinster (https://arxiv.org/pdf/1612.09375)
Category Theory in Context by Emily Riehl (https://emilyriehl.github.io/files/context.pdf)
Basic Category Theory by Tom Leinster (https://arxiv.org/pdf/1612.09375)