Djordje Popovic Giby Raphael Robin Johnson Gene Davis Chris Berka Wearable Modular Device for Facilitation of Napping and Optimization of Post-nap Performance. 289-298 2009 HCI (16) http://dx.doi.org/10.1007/978-3-642-02812-0_34 conf/hci/2009-16 db/conf/hci/hci2009-16.html#PopovicRJDB09