#1 IS, author of Sasol Birds of Southern Africa, South African ornithologist b.1948.
#2 IS, author of Practical Electronics Handbook, is Ian Robertson Sinclair, a prolific writer of technical works. He has another author page under his full name.
#3 IS, author of Fostering Now, writes on sociolgical issues, b.1938.
#4 IS, author of Health The Only Immunity, is an Australian writer on popular health issues.
The unknown work, 'Hopi Mean Time', is an article (review) from the London Review of Books and is probably by Iain Sinclair.