Search for "triphenylphosphine oxide (TPPO)" in Full Text gives 2 result(s) in Beilstein Journal of Organic Chemistry.
Beilstein J. Org. Chem. 2016, 12, 1758–1764, doi:10.3762/bjoc.12.164
Beilstein J. Org. Chem. 2012, 8, 11–17, doi:10.3762/bjoc.8.2