Access QGIS to download QGIS for Mac OS, Windows, and Linux, with additional information on getting started with QGIS, getting involved with contributions to the QGIS development and troubleshooting, and learning more about QGIS

Includes links to the QGIS User Guide in both web and pdf format for current and past versions, and includes link to an introduction to GIS basics

Web-version of the QGIS user guide

Includes listing of GIS operation by categories of basic, intermediate, and advanced operations, along with helpful tips and tricks

Comparison of features of ArcGIS And QGIS

University of Iowa's Library QGIS for Beginners tutorial

Instructional materials for QGIS related to choropleth maps, layers, georeferencing, digitizing, adding points, and adding basemaps

OpenStreetMap homepage

includes how to use raster and vector data from OSM in QGIS.

Description of various ways of downloading OpenStreetMap data

Includes tutorial for various plugins (e.g., QuickOSM)

GDAL homepage, which includes the links to download site, tutorial, api references, and community lists.

PostGIS homepage, which includes the links to download site, documentation and development.

This text provides readers with examples of install R, using R functions, using R packages, along with working with working with multiple data formats.

This site provides tutorial information on working with R and geographic data.

This site provides a set of tutorials for using R with spatial data, including data to use with tutorials.

Includes instruction on working with spatial data in R, including creating and manipulating spatial data, and making maps

This research article provides examples uses of ggmap and ggplot2.

This text provides information on working with R using multiple functions and examples.

This mailing list is the portion of the larger R community dedicated to addressing spatial problems in R.

Includes R manuals in web, pdf, and EPUb formats, including “An Introduction to R, R Data Import/Export, and R Installation and Administration.”

Provides an introduction to R with links for download options, the R Foundation, and Documentation

This site includes tutorials for R working with spatial data.

This tutorial provides an introduction to using R with geospatial data, including loading geospatial packages, geospatial data formatting, and plotting a map.

This lesson includes downloading R, creating an ArcGIS Project, and installing the R-ArcGIS bridge, along with aggregation of point data by counts, and analysis of crime hot spots.
Note when using the R-ArcGIS Bridge, library used is the arcgisbinding library, new functions include:
arc.check_product(): Prints information about ArcGIS product; arc.open(): creates a new arc.dataset class object; arc.select(): selects a subject of attributes from arc.dataset class object; arc.data2sp(): converts R data frame into a spatial object

The R – ArcGIS Community is a community driven collection of free, open source projects making it easier and faster for R users to work with ArcGIS data, and ArcGIS users to leverage the analysis capabilities of R." Includes downloads on GitHub and discussion on Geonet

Provides access to download GeoD, and other related open source software

Provides open educational materials related to software used in the online course, including “QGIS, GDAL, OGR, GeoServer, TileMill, OpenLayers, and OpenStreetMap”.

Access the SAGA homepage for download, introduction, FAQs, and references

Includes links to how to cite SAGA, manuals, tutorials, guides, and publications that use SAGA

Provides access to the GRASS GIS homepage with information on download options for Mac OSX, Windows, and Linux, with related links on documentation, gallery, support, and development

Includes general overview, first time users, manuals, applications, FAQs, and links to online references that use GRASS for research purposes

Includes Examples of applications using GRASS