http://uva.anahuac.mx/content/catalogo/diplanes/modulos/mod2/l1t3m2.htm

https://www.youtube.com/watch?v=8iBW3nejTKM

https://www.youtube.com/watch?v=U4OLJNDNHxM

http://www.slideboom.com/presentations/162486/Diagramas-PERT---ISIV---DS-I

Creo que el predecesor de F es E

http://www.cs.nott.ac.uk/~jds/teaching/archive/G52LSSLecture6.pdf