Best book on tells

[Foucault]

Caro does cover Hold 'Em and a lot of his examples are widely applicable. Only a few are specific to draw poker, and even beyond his specific examples, his general approach to reading people (distinguishing between acting and non-acting tells, strong means weak, etc.) is very valuable. It's only dated in the sense that a lot of people have read it and sometimes employ reverse tells, but it's still a very valuable resource.