@Article{JPDE-1-43, author = {M. Y. Chi}, title = {On a Class of Partial Differential Equations of Mixed Type}, journal = {Journal of Partial Differential Equations}, year = {1988}, volume = {1}, number = {1}, pages = {43--52}, abstract = {}, issn = {2079-732X}, doi = {https://doi.org/}, url = {http://global-sci.org/intro/article_detail/jpde/5851.html} }