30 ggplot basics | The Epidemiologist R Handbook
r - ggplot2 - filling in manual shapes with manual colors - Stack Overflow
15 Scales and guides | ggplot2
ggplot2 point shapes - Easy Guides - Wiki - STHDA
5.3 Using Different Point Shapes | R Graphics Cookbook, 2nd edition
Request: support providing shapes as names rather than integers · Issue #2075 · tidyverse/ggplot2 · GitHub
Set guides for each scale — guides • ggplot2
ggplot2 point shapes - Easy Guides - Wiki - STHDA
How to use more than 6 shapes in qplot? | ResearchGate
r - Changing shapes used for scale_shape() in ggplot2 - Stack Overflow
Request: support providing shapes as names rather than integers · Issue #2075 · tidyverse/ggplot2 · GitHub
GGPLOT Point Shapes Best Tips - Datanovia
Controlling legend appearance in ggplot2 with override.aes | R-bloggers
GGPLOT Point Shapes Best Tips - Datanovia
Shapes and line types
Shape characteristic in ggplot2 - tidyverse - RStudio Community
r - ggplot multiple manual shape series - Stack Overflow
Scales for shapes, aka glyphs — scale_shape • ggplot2
Controlling legend appearance in ggplot2 with override.aes | R-bloggers
How to Change Point Shape in ggplot2 - Statology
Point Shape Options in ggplot - Albert's Blog
Shapes and line types
Aesthetic specifications • ggplot2
