.

Poorter, Hendrik, et al. Causes and consequences of variation in leaf mass per area (LMA) a meta‐analysis. New phytologist 182.3 (2009) 565-588. LMA could be interpreted to sum of leaf tissue types, such as epidermis, mesophyll and vascular tissue, which have different density.

Schaepman-Strub, Gabriela, et al. Reflectance quantities in optical remote sensing—Definitions and case studies. Remote sensing of environment 103.1 (2006) 27-42. If a surface was not an ideal specular or diffuse surface, one could observe diffuse light as well as specular light reflected off the surface. Reflectance is affected by where the incident light comes from and where the light is observed, which is represented by an angular distribution function. So different reflectance concepts are possible, so it is needed to use the term reflectance practically.