https://gsrpdf.lib.msu.edu/?file=/2000s/2008/080912.pdf | 01/26/2017 | PDF Reader | | |
https://gsrpdf.lib.msu.edu/?file=/article/138786-Z[...] | 07/11/2018 | PDF Reader | | Mandarin version |
https://gsrpdf.lib.msu.edu/?file=/article/138786-SP.pdf | 07/11/2018 | PDF Reader | | Spanish version |