List of Articles Silica-bonded n-propyldiethylenetriamine sulfamic acid Open Access Article Abstract Page Full-Text 1 - Silica-bonded n-propyldiethylenetriamine sulfamic acid as a recyclable solid acid catalyst for the synthesis of coumarin and biscoumarin derivatives Khodabakhsh Niknam Seyed Ahmad Sajadi Roghayeh Hosseini Mojtaba Baghernejad