TY - GEN AU - William C Cullen AU - William W Walton C2 - , National Institute of Standards and Technology, Gaithersburg, MD DA - 1961-01-01 05:01:00 DO - https://doi.org/10.6028/NBS.RPT.7065 LA - en PB - , National Institute of Standards and Technology, Gaithersburg, MD PY - 1961 TI - The soiling characteristics of structural masonry units ::report ER -