http://www.agoracactus.com.ar/foros/index.php
http://www.mammillarias.net
http://www.haworthia.info/en/gallery/01.html
http://www.echeveriasinoz.com/photos2.html
http://www.geocities.com/yaxkinmex/Tablatrat.html
http://www.villadia.net/
http://www.collectorscorner.com.au/Cacti/Crassula%201.htm
http://www.lapshin.org/succulent/!cras.htm
http://cactomania.galeon.com/crasas.htm
http://www.gasteria.org/descriptions.htm