Item #14: Ïðÿìîé ïîïåðå÷íûé èçãèá ïðèçìàòè÷åñêîãî ñòåðæíÿ
In Russian this name is written as Æóðàâñêèé
This formula defined the average shear stress for transverse bending of beams having any cross-sectional shape.
You can find it (although with very poor explanation) in the standard text for the students. For example Eq. (5.10) in F.P.Beer and E.R.Johnson, Jr., Mechanics of Materials, SI Metric Edition, McGraw-Hill 1985.
1. Find any textbook on mechanics of materials
2. Find a chapter (section) “Shearing stresses in thin-walled members
3. Find formula
tau(eve)=(VQ)/(It)