The shear stress
at which yielding starts abruptly. Its value depends on the criterion used to determine
when yielding occurs.
PAC, 1979, 51, 1213
(Manual of symbols and terminology for physicochemical quantities and units. Appendix
II: Definitions, terminology and symbols in colloid and surface chemistry. Part 1.13.
Selected definitions, terminology and symbols for rheological properties)
on page 1217