Add references for ASM

[YHordijk]

We should add citations for the activation strain model:

Handbook
For a step-by-step protocol, see: (a) Vermeeren, P.; van der Lubbe, S. C. C.; Fonseca Guerra, C.; Bickelhaupt, F. M.; Hamlin, T. A. Understanding Chemical Reactivity Using the Activation Strain Model. Nat. Protoc. 2020, 15, 649–667. for reviews, see: (b) Bickelhaupt, F. M. Understanding Reactivity with Kohn-Sham Molecular Orbital Theory: E2–SN2 Mechanistic Spectrum and Other Concepts J. Comp. Chem. 1999, 20, 114–128. (c) van Zeist, W.-J.; Bickelhaupt, F. M. The Activation Strain Model of Chemical Reactivity. Org. Biomol. Chem. 2010, 8, 3118–3127. (d) Fernández, I.; Bickelhaupt, F. M. The Activation Strain Model and Molecular Orbital Theory: Understanding and Designing Chemical Reactions Chem. Soc. Rev. 2014, 43, 4953–4967. (e) Wolters, L. P.; Bickelhaupt, F. M. The Activation Strain Model and Molecular Orbital Theory. WIRES Comput. Mol. Sci. 2015, 5, 324–343. (f) Bickelhaupt, F. M.; Houk, K. N. Analyzing Reaction Rates with the Distortion/Interaction-Activation Strain Model. Angew. Chem. 2017, 129, 10204–10221; Angew. Chem. Int. Ed. 2017, 56, 10070–10086. (g) Vermeeren, P.; Hamlin, T. A.; Bickelhaupt, F. M. Chemical Reactivity from an Activation Strain Perspective Chem. Comm. 2021, 57, 5880–5896.

DOIS
(a) 10.1038/s41596-019-0265-0
(b) 10.1002/(SICI)1096-987X(19990115)20:1<114::AID-JCC12>3.0.CO;2-L
(c) 10.1039/B926828F
(d) 10.1039/C4CS00055B
(e) 10.1002/wcms.1221
(f) 10.1002/anie.201701486
(g) 10.1039/D1CC02042K