replaced linked reference with textual reference due to broken links

Author: dafnidrake

episodes/11-vector-raster-integration.Rmd

@@ -305,8 +305,8 @@ for example, plot locations that we are sampling on the ground. We can extract
 all pixel values within 20m of our x,y point of interest. These can then be 
 summarized into some value of interest (e.g. mean, maximum, total).
 
-![](fig//BufferSquare.png){alt='Image shows raster information extraction using 20m polygon boundary'}
-Image Source: https://www.neonscience.org/sites/default/files/images/spatialData/BufferSquare.png
+![](fig//BufferSquare.png){alt='Image shows raster information extraction using 20m polygon boundary.'}
+Image Source: National Ecological Observatory Network (NEON)
 
 To do this in R, we use the `extract()` function. The `extract()` function
 requires:
@@ -380,9 +380,7 @@ CRS. All pixels that are touched by the buffer region are included in the
 extract.
 
 ![](fig/BufferCircular.png){alt='Image shows raster information extraction using 20m buffer region.'}
-Image Source: https://www.neonscience.org/sites/default/files/images/spatialData/BufferCircular.png
-
-Source: National Ecological Observatory Network (NEON).
+Image Source: National Ecological Observatory Network (NEON)
 
 Let's put this into practice by figuring out the mean tree height in the 20m 
 around the tower location (`point_HARV`).