Navy:10.1580/0953-9859-2.3.206
Navy:10.1580/0953-9859-3.2.168
Navy:10.1580/1080-6032(1999)010[0066:EOASOU]2.3.CO;2
Navy:10.1580/1080-6032(2002)013[0094:OSIHTI]2.0.CO;2