https://digitalcommons.unl.edu/sramdiss/ 2017-12-04 https://digitalcommons.unl.edu/sramdiss/1/ 2007-07-13 https://digitalcommons.unl.edu/sramdiss/2/ 2010-04-07 https://digitalcommons.unl.edu/sramdiss/3/ 2010-05-18 https://digitalcommons.unl.edu/sramdiss/4/ 2011-07-27 https://digitalcommons.unl.edu/sramdiss/5/ 2012-07-19 https://digitalcommons.unl.edu/sramdiss/6/ 2014-12-01 https://digitalcommons.unl.edu/sramdiss/7/ 2015-07-26 https://digitalcommons.unl.edu/sramdiss/8/ 2015-07-26 https://digitalcommons.unl.edu/sramdiss/9/ 2016-12-09 https://digitalcommons.unl.edu/sramdiss/10/ 2017-03-23 https://digitalcommons.unl.edu/sramdiss/11/ 2017-08-03 https://digitalcommons.unl.edu/sramdiss/12/ 2017-12-04