@article{oai:tsukuba.repo.nii.ac.jp:00029690,
 author = {Dragomir, Sorin and Lanconelli, Ermanno},
 issue = {1},
 journal = {Tsukuba Journal of Mathematics},
 month = {Jun},
 pages = {149--170},
 title = {On first order linear PDE systems all of whose solutions are harmonic functions},
 volume = {30},
 year = {2006}
}