1. XBee 868 Pro specifications,
http://www.digi.com/products/wireless-wired-embedded-solutions/zigbee-rf-modules/point-multipoint-rfmodules/xbee-pro-868#specs
2. A1084 GPS receiver hardware manual,
http://ec-mobile.ru/user_files/File/Tyco/A1084_HM_V1.0.pdf
3. Libelium’s Waspmote manual,
http://www.libelium.com/v11-files/documentation/waspmote/waspmote-technical_guide_eng.pdf
4. PNI’s legacy TCM2.5 electronic compass manual,
http://www.pnicorp.com/download/347/99/TCM2.52.6Manualr09.pdf
5. US Digital absolute encoder MA3,
http://www.usdigital.com/products/encoders/absolute/rotary/shaft/ma3