As discussed during the February GIS User Council meeting, it is good practice to cite data sources when including them in any sort of report, presentation or web application. To that end, citation information has been added to the GIS Hub page just below the data search icons: https://egis-lacounty.hub.arcgis.com/
There is also a link there for (updated) information on citing the LARIAC imagery data.
Of course, when using data from other (non County) sources, you can/should follow a similar format (e.g. data from other local, state, federal sources, Esri Living Atlas, etc.)