1. Hutchinson et al (2006) United States Patent No. 7,134,397
2. Yasuda Y, Motomura T (2009) Japanese Patent No. 2011-75183. Japanese Patent Office, Tokyo
3. Yasuda Y, Motomura T (2009) Japanese Patent No. 2011075184. Japanese Patent Office, Tokyo
4. Motomura T, Okamura H (2010). Japanese Patent No. 2012-57905. Japanese Patent Office,Tokyo
5. Motomura T, Okamura H (2014) Japanese Patent No. 2015-197227. Japanese Patent Office, Tokyo