Robuta

https://store.astm.org/e0580_e0580m-10a.html E580/E580M Standard Practice for Installation of Ceiling Suspension Systems for Acoustical Tile and... ceiling suspension systems https://store.astm.org/e0580_e0580m-09a.html E580/E580M Standard Practice for Installation of Ceiling Suspension Systems for Acoustical Tile and... ceiling suspension systems https://patents.google.com/patent/US3440947A/en US3440947A - Combination diffuser and false ceiling suspension systems - Google Patents ceiling suspension systemscombinationdiffuserfalsegoogle