http://www.tps.ac.th/~narin/basicchem/index_files/page0009.htm
http://www.lks.ac.th/student/kroo_su/chem7/type_of_hydrocarbon.htm
http://web.ku.ac.th/schoolnet/snet5/topic8/c_carbon.html
http://www.proprofs.com/quiz-school/story.php?title=sasasasa_13
http://dcsl.srp.ac.th/content/sci/sec4/chem/cai/chemistry/chem4018/hydrocarbon/CH-properties.htm