8Pitkala K, Kahonen-Vare M, Valvanne J, et al. Long-term changes in mood of an aged population: repeated Zung-tests during a 10-year follow-up[J]. Arch Gerontol Geriatr, 2003, 36(2): 185-195.
9Hope K. A hidden problem: identifying depression in older people[J]. Br J Community Nurs, 2003, 8(7): 314-320.