diff --git a/material-Stefan/orbiAlb1.pdf b/material-Stefan/orbiAlb1.pdf new file mode 100644 index 0000000..1bc9d05 Binary files /dev/null and b/material-Stefan/orbiAlb1.pdf differ diff --git a/material-Stefan/orbiAlb2.pdf b/material-Stefan/orbiAlb2.pdf new file mode 100644 index 0000000..e111c4f Binary files /dev/null and b/material-Stefan/orbiAlb2.pdf differ diff --git a/material-Stefan/orbiAlb3.pdf b/material-Stefan/orbiAlb3.pdf new file mode 100644 index 0000000..b95870d Binary files /dev/null and b/material-Stefan/orbiAlb3.pdf differ