Tzvetan OstromskyPer Christian HansenZahari ZlatevA Coarse-Grained Parallel QR-Factorization Algorithm for Sparse Least Squares Problems.937-964199824Parallel Comput.5-6db/journals/pc/pc24.html#OstromskyHZ98https://doi.org/10.1016/S0167-8191(98)00034-9