Mike X Cohen - Analyzing Neural Time Series Data (The MIT Press, 2014) – probably the best book in DSP (it has “neural” in the title, but the concepts are more general)
Steven J. Luck - An Introduction to the Event-Related Potential Technique (Bradford Book, 2014) – the second important book in DSP; strongly aimed at EEG signals (a bible for ERP researchers), but also useful in other domains