Mobile Diary for Wellness Management - Results on Usage and Usability in Two User Studies. - Elina M. Mattila; Juha Pärkkä; Marion Hermersdorf; Jussi Kaasinen; Janne Vainio; K. Samposalo; Juho Merilahti; Juha Kolari; Minna Kulju; Raimo Lappalainen; Ilkka Korhonen (IEEE Trans. Inf. Technol. Biomed., 2008)