RICCI-FLAT SPACES WITH A METRIC OF SPECIAL FORM СтатьяKorrèa Kh., Ryzhkov V.V.Webs and quasigroups (Russian). 1990. С. 95-97
THE SECOND BOUNDARY VALUE PROBLEM FOR A PARABOLIC DIFFERENTIAL-DIFFERENCE EQUATION СтатьяSelitskiĭ A.M., Skubachevskiĭ A.L.Успехи математических наук. 2007.