I've been trying to self study the section on de Rham cohomology in Guillemin and Pollack's book Differential Topology. The section is in a sense hands on: most of the results are presented as exercises scattered throughout the section, and some hints are given. I've hit a road block in a few of the exercises and have been searching for a book, some online course notes or some other reference on de Rham cohomology to help me through the exercises I'm stuck on. However, Guillemin and Pollack use slightly different definitions than all of the other books or notes I've been able to find. I'd like to find a book, set of notes, or some other reference that uses similar definitions to Guillemin and Pollack. Can anyone who is familiar with Guillemin and Pollack's book point me in the direction of an alternate reference that treats de Rham cohomology in a similar manner to GP? Thank!