http://www.hmms2015.ru/files/Contributions/Preliminary%20study%20of%20the%20work%20of%20Xu%20Guangqi%20in%20the%20technical%20knowledge%20in%2017th%20century%20from%20the%20perspective%20of%20drawing%20and%20representation.pdf
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http://webuser.unicas.it/cigola/pub/Articoli/15_StPeterburg.pdf
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http://www.researchgate.net/profile/Michela_Cigola/publication/277198247_Preliminary_study_of_the_work_of_Xu_Guangqi_in_the_technical_knowledge_in_17th_century_from_the_perspective_of_drawing_and_representation/links/557948aa08aeb6d8c01f22c8.pdf
ResearchGate
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http://hmms2015.ru/files/Contributions/Preliminary%20study%20of%20the%20work%20of%20Xu%20Guangqi%20in%20the%20technical%20knowledge%20in%2017th%20century%20from%20the%20perspective%20of%20drawing%20and%20representation.pdf
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