\(Pic1\  = \ 
      Plot3D[\ Sin[x\ y], \ {x, \ 0, 3}, {y, \ 0, 
          4}, 
Ticks -> 
          False, 
Boxed -> 
          True, 
Axes -> 
          False, 
PlotLabel -> "A"]
\)
Pic2  =  
      Plot3D[ Cos[x y],  {x,  0, 3}, {y,  0, 
          4}, 
Ticks -> 
          False, 
Boxed -> 
          True, 
Axes -> 
          False]

Pic3  =  
      Plot3D[ Sin[x  + y],  {x,  0, 3}, {y,  0, 
          4}, 
Ticks -> 
          False, 
Boxed -> 
          True, 
Axes -> 
          False]

Pic4  =  
      Plot3D[ Cos[x  +  y^2],  {x,  0, 3}, {y,  0, 
          4}, 
Ticks -> 
          False, 
Boxed -> 
          True, 
Axes -> False]

Show[
GraphicsArray[
{
{Pic1, Pic2}, 
{Pic3, 
            Pic4}
}, 
GraphicsSpacing -> 0
], 
Frame -> 
        True
]