Available at the Family History Library.
At the Bartrum Project website, this work and Welsh Genealogies AD 1400-1500 are scanned and available online.
Pedigree charts are organized by the founders of lineages. For example, Cynwrig ab Owain, a direct male-line descendant of Tudor Trefor, is found with his siblings on the chart "Tudor Trefor 10". Entering "Tudor Trefor 10" in the search bar will take you to his chart. If you do not already know which chart he is on, some browsing of charts starting with "Tudur Trefor" may be required. Underlined names on a chart followed by a number are the titles of other charts with more information. The digitization project is ongoing, and as of 2013 only partially complete.
FHL film numbers