skyvector dot com has all the avcharts with frequencies shown - KDMA is identifier for D-M. Don't forget to check Tucson too. Phoenix chart has many VHF and UHF freqs - current version. Enroute Lo (L-5) and Enroute Hi (H-4) have more. If you see a TFR pop-up (pink outlined in orange, they will sometimes list 'unusual' frequencies to add to your list. E.g., FHU has an ongoing TFR for their UAV work.
airnav dot com has detailed frequencies for airports - use their ID to locate the information. KDMA, KTUS, KFHU, etc. Ground and similar frequencies are on the Airport Diagram on right side of page if available. For more info related to freq's used on approaches open the links to the approach or departure procedures down the page, e.g., Hi-TACAN Z RWY 12 or ILS OR LOC Y RWY 30. The Additional Remarks section often list more freqs - for example at DM you call for fuel on 372.2 30 minutes prior to arrival. (Sometimes some funny stuff too like 'CAUTION: COYOTES, BURROWING OWLS AND JAVELINAS FOUND OCNL ON BOTH SIDES OF RWY.")
