References for the numbering systems

Col	Reference

---	---------

R1	Hakkila J., Sanders W.L., Schroder R. 1983, Astr. Ap. Suppl. 51, 541

R2	Hoag A.A., et al. 1961, Publ. US Nav. Obs. 17, 347  (pe)

R3	Hoag A.A., et al. 1961, Publ. US Nav. Obs. 17, 347  (pg)

R4	Mathews R.T. 1963, Publ. Goodsell Obs. no 14

R5	Latypov A.A. 1977, Tsirk. Astr. Obs. Tashkent no 74

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