TY - RPRT TI - Almost sharp fronts for the surface quasi-geostrophic equation. AU - Diego Córdoba AU - Charles Fefferman AU - José Luis Rodrigo PY - 2004 DO - 10.1073/pnas.0308154101 UR - https://pubmed.ncbi.nlm.nih.gov/14978276/ ID - 14978276 ER -