Read the seminal paper by Becker entitled 2,2-Dimethylpropvlidynephosphine, a Stable Compound with a Phosphorus Atom of Coordination Number 1 and come to class prepared to discuss it.
Read also the article by Becker constituting an early report of isolation of the phosphaethynolate ion and come to class prepared to discuss it.
Follow the impact of the Becker papers to the present day by reading one or more recent papers that cite them. Come prepared to discuss the recent Becker-citing work as well.
Read Gillespie's paper entitled Gilbert N. Lewis and the chemical bond: The electron pair and the octet rule from 1916 to the present day. Pay special attention to the discussion of Linnett's Double Quartet theory (LDQ theory) and the electron localization function (ELF), a topological analysis comparable to AIM and available also in MultiWFN.
Note that LDQ theory was a reasoned approach to deducing the most probable distribution of electrons in a molecule, including electron correlation effects, Pauli repulsion, and Coulomb repulsion. A seminal paper has appeared showing that these most probable electron positions can be extracted from Ψ2.