Comparison Internal vs External Fertilisation

Some useful sites:

http://www.bgetutor.com/Library/C33.html

http://www.scienceclarified.com/Ex-Ga/Fertilization.html

http://books.google.com.au/books?id=jlIW75Mc0QUC&pg=PA87&lpg=PA87&dq=external+fertilisation&source=bl&ots=lDp4FmRV6d&sig=ujhkGtI8Ho3EusMrSsArTRpm3R0&hl=en&ei=lCh_TPioLcqXcZKZnZwL&sa=X&oi=book_result&ct=result&resnum=9&ved=0CDYQ6AEwCDg8#v=onepage&q=external%20fertilisation&f=false

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