[1] V. Quaresima, M. Ferrari, "A mini-review on functional near-infrared spectroscopy (fNIRS): Where do we stand, and where should we go?" Photonics, 6, 87 (2019).

[2] S. Jones, S. T. Chiesa, N. Chaturvedi, A. D. Hughes, "Recent developments in near-infrared spectroscopy (NIRS) for the assessment of local skeletal muscle microvascular function and capacity to utilize oxygen," Artery Res. 16, 25–33 (2016).

[3] D. Grosenick, H. Rinneberg, R. Cubeddu, P. Taroni, "Review of optical breast imaging and spectroscopy," J. Biomed. Opt. 21, 091311 (2016).

[4] R. B. Saager, A. J. Berger, "Direct characterization and removal of interfering absorption trends in two-layer turbid media," J. Opt. Soc. Am. A 22, 1874–1882 (2005).

[5] Q. Zhang, E. N. Brown, G. E. Strangman, "Adaptive filtering for global interference cancellation and real-time recovery of evoked brain activity: A Monte Carlo simulation study," J. Biomed. Opt. 12, 044014 (2007).

[6] L.Gagnon, K. L. Perdue, D. N. Greve, D.Goldenholz, G. Kaskhedikar, D. A. Boas, "Improved recovery of the hemodynamic response in diffuse optical imaging using short optode separations and statespace modeling," NeuroImage, 56, 1362–1371 (2011).

[7] T. Funane, H. Atsumori, T. Katura, A. N. Obata, H. Sato, Y. Tanikawa, E. Okada, M. Kiguchi, "Quantitative evaluation of deep and shallow tissue layers' contribution to fNIRS signal using multidistance optodes and independent component analysis," NeuroImage, 85, 150–165 (2014).

[8] L. Gagnon, M. A. Yucel, M. A. D. A. Boas, R. J. Cooper, "Further improvement in reducing superfi-cial contamination in NIRS using doubleshort separation measurements," NeuroImage, 85, 127–135 (2014).

[9] J. Steinbrink, H. Wabnitz, H. Obrig, A. Villringer, H. Rinneberg, "Determining changes in NIR absorption using a layered model of the human head," Phys. Med. Biol. 46, 879–896 (2001).

[10] B. Hallacoglu, A. Sassaroli, S. Fantini, "Optical characterization of two-layered turbid media for non-invasive, absolute oximetry in cerebral and extracerebral tissue," PLoS ONE 8, e64095 (2013).

[11] N. M. Gregg, B. R. White, B. W. Zeff, A. J. Berger, J. P. Culver, "Brain specificity of diffuse optical imaging: Improvements from superficial signal regression and tomography," Front. Neuroenerg. 2, 14 (2010).

[12] S. Feng, F. Zeng, B. Chance, "Photon migration in the presence of a single defect: A perturbation analysis," Appl. Opt. 34, 3826–3837 (1995).

[13] M. A. Franceschini, S. Fantini, L. A. Paunescu, J. S. Maier, E. Gratton, "Influence of a superficial layer in the quantitative spectroscopic study of strongly scattering media," Appl. Opt. 37, 7447–7458 (1998).

[14] S. Suzuki, S. Takasaki, T. Ozaki, Y. Kobayashi, "A tissue oxygenation monitor using NIR spatially resolved spectroscopy," Proc. SPIE 3597, 582–592 (1999).

[15] D. Milej, A. Abdalmalak, P. McLachlan, M. Diop, A. Liebert, K. St. Lawrence, "Subtraction-based approach for enhancing the depth sensitivity of time-resolved NIRS," Biomed. Opt. Exp. 7, 4514–4526 (2016).

[16] A. Sassaroli, G. Blaney, S. Fantini, "Dual-slope method for enhanced depth sensitivity in diffuse optical spectroscopy," J. Opt. Soc. Am. A 36, 1743–1761 (2019).

[17] G. Blaney, A. Sassaroli, T. Pham, C. Fernandez, S. Fantini, "Phase dual-slopes in frequency-domain near-infrared spectroscopy for enhanced sensitivity to brain tissue: First applications to human subjects," J. Biophoton. e201960018 (2019).

[18] P. Sawosz, A. Liebert, "Method to improve the depth sensitivity of diffuse reflectance measurements to absorption changes in optically turbid medium," Biomed. Opt. Exp. 10, 5031–5041 (2019).

[19] D. M. Hueber, S. Fantini, A. E. Cerussi, B. Barbieri, "New optical probe designs for absolute (selfcalibrating) NIR tissue hemoglobin measurements," Proc. SPIE 3597, 618–631 (1999).

[20] J. C. Schotland, J. C. Haselgrove, J. S. Leigh, "Photon hitting density," Appl. Opt. 32, 448–453 (1993).

[21] S. R. Arridge, "Photon-measurement density functions. Part I: Analytical forms," Appl. Opt. 34, 7395–7409 (1995).

[22] I. J. Bigio, S. Fantini, Quantitative Biomedical Optics: Theory, Methods, and Applications, Cambridge University Press, Cambridge, UK (2016).

[23] A. Sassaroli, F. Martelli, S. Fantini, "Perturbation theory for the diffusion equation by use of the moments of the generalized temporal pointspread function. I. Theory," J. Opt. Soc. Am. A 23, 2105–2118 (2006).

[24] D. T. Delpy, M. Cope, P. van der Zee, S. Arridge, S. Wray, J. Wyatt, "Estimation of optical path length measurements on adult head, calf, and forearm and the head of newborn infants using phase resolved spectroscopy," Phys. Med. Biol. 40, 295–304 (1988).

[25] A. Sassaroli, S. Fantini, "Comment on the modified Beer-Lambert law for scattering media," Phys. Med. Biol. 49, N255–N257 (2004).

[26] D. Contini, F. Martelli, G. Zaccanti, "Photon migration through a turbid slab described by a model based on diffusion approximation. I. Theory," Appl. Opt. 36, 4587–4599 (1997).

[27] S. Fantini, M. A. Franceschini, S. A. Walker, J. S. Maier, E. Gratton, "Photon path distributions in turbid media: Applications for imaging," Proc. SPIE 2389, 340–349 (1995).

[28] A. Liebert, H. Wabnitz, J. Steinbrink, H. Obrig, M. M€oller, R. Macdonald, A. Villringer, H. Rinneberg, "Time-resolved multidistance near-infrared spectroscopy of the adult head: Intracerebral and extracerebral absorption changes from moments of distribution of time of flight of photons," Appl. Opt. 43, 3037–3047 (2004).

[29] M. Doulgerakis, A. Eggebrecht, H. Dehghani, "Information rich phase content of frequency domain functional near-infrared spectroscopy," Proc. SPIE 10865, 108650C (2019).

[30] G. Blaney, A. Sassaroli, T. Pham, N. Krishnamurthy, S. Fantini, "Multi-distance frequency-domain optical measurements of coherent cerebral hemodynamics," Photonics, 6, 83 (2019).

[31] H. Gu, H. Lu, F. Q. Ye, E. A. Stein, Y. Yanga, "Noninvasive quantification of cerebral blood volume in humans during functional activation," NeuroImage, 30, 377–387 (2006).