Removing sources from higher-rank graphs
  For a higher-rank graph $\Lambda$ with sources we detail a construction that creates a higher-rank graph $\bar{\Lambda}$ that does not have sources and contains $\Lambda$ as a subgraph. Furthermore, when $\Lambda$ is row-finite, the Cuntz-Krieger algebra of $\Lambda$ is a full corner of $C^*(\bar{\Lambda})$, the Cuntz-Krieger algebra of $\bar{\Lambda}$. 
Cynthia Farthing