@article{MAN_1988__282_2_164450, author = {Masaaki Yoshida and Takeshi Sasaki}, title = {Linear differential {Equations} in {Two} {Variables} of {Rank} {Four.} {I.}}, journal = {Mathematische Annalen}, pages = {69--94}, publisher = {mathdoc}, volume = {282}, number = {2}, year = {1988}, zbl = {0627.35014}, url = {http://geodesic.mathdoc.fr/item/MAN_1988__282_2_164450/} }