كهف تشيفيه

http://philippelopes.free.fr/SistemaCheve.htm

وفي السياق ذاته، https://books.google.com/books?id=vPVJlRi91bwC&pg=PA4&lpg=PA4&dq=sistema+Cheve&source=bl&ots=0XgMDPA0V_&sig=zyWAlHf9UKo9DCLqeuOnvnVKkVw&hl=en&sa=X&ei=A1vRVM7TMYOfgwSAq4PgAg&ved=0CCgQ6AEwBDge#v=onepage&q=sistema%20Cheve&f=false

من جهة ثانية، https://books.google.com/books?id=MY0PAQAAQBAJ&pg=RA1-PA270&lpg=RA1-PA270&dq=sistema+Cheve&source=bl&ots=2FHSDMsKxG&sig=B7Qimo8i6ZrEuoGv2ytM0yo9Ex4&hl=en&sa=X&ei=A1vRVM7TMYOfgwSAq4PgAg&ved=0CCsQ6AEwBTge#v=onepage&q=sistema%20Cheve&f=false

وفي هذا الصدد، https://books.google.com/books?id=KDy2AgAAQBAJ&pg=PA32&lpg=PA32&dq=sistema+Cheve&source=bl&ots=RVsky8wozh&sig=HsBkRm1rAKshd4pHF4g_cQ2RFus&hl=en&sa=X&ei=A1vRVM7TMYOfgwSAq4PgAg&ved=0CB4Q6AEwATge#v=onepage&q=Cheve&f=false