no. 2
The projective invariants of the configuration of two lines and a third order differential element
Rendiconti del Seminario Matematico della Università di Padova, Tome 35 (1965) no. 2, pp. 365-370. 
@article{RSMUP_1965__35_2_365_0,
     author = {Angotti, Rodney},
     title = {The projective invariants of the configuration of two lines and a third order differential element},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {365--370},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {35},
     number = {2},
     year = {1965},
     mrnumber = {211336},
     zbl = {0139.15103},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1965__35_2_365_0/}
}
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Angotti, Rodney. The projective invariants of the configuration of two lines and a third order differential element. Rendiconti del Seminario Matematico della Università di Padova, Tome 35 (1965) no. 2, pp. 365-370. http://www.numdam.org/item/RSMUP_1965__35_2_365_0/

[1] Bompiani E.: Configuration associées à un élément curviligne du troisième ordre dans l'espace projectif, Journal des Math. pures et appl. 41 (1962). | MR | Zbl