$\backslash$table$[[$Quantity$,\backslash$table$[[$Simple Cubic$],[($SC$)]],\backslash$table$[[$Body$-$Centered$],[$Cubic $($BCC$)]],\backslash$table$[[$Face$-$Centered$],[$Cubic $($FCC$]],\backslash$table$[[$Hexagonal$],[$Close$-$Packed$],[($HCP$)]]],[\backslash$table$[[$Sketch of unit$],[$cell $($hard$-],[$and$/$or$],[$reduced$-$sphere$],[$model$)]]],[\backslash$table$[[$Number of$],[$atoms per unit$],[$cell$]]],[\backslash$table$[[$Atoms touch$],[$along which$],[$direction$?]]],[\backslash$table$[[$# atomic radii$],[$along touching$],[$direction within$],[$unit cell?$]],$#$R=,$#$R=,$#$R=,],[\backslash$table$[[$Unit cell edge$],[$length $($i$.$e$.,],[$lattice$],[$constant$)],[$in terms of R$]],a=,a=,a=,],[\backslash$table$[[$Unit cell$],[$volume$],[$in terms of $R$