Some of the most popular of the recent sales and selling books are detailed below. While they are not written specically for scientific sales jobs, the principals of successful selling apply.
Amazon.co.uk have a powerful search facility for finding books on sales jobs and selling techniques and on a number of titles you can also view selected excerpts to give you a feel of the writer's style and approach to the subject.
Some of the books we would recommend for scientific sales jobs are:
SPIN-selling
(Situation Problem Implication Need- payoff) Neil Rackman
What makes success in major sales.
How some sales people consistently outsell their competition.
Why closing techniques work in smaller sales but not larger ones
How sales people can dramatically increase their sales volume from major accounts
Differentiate yourself from your competition and dispel negative stereotypes.
Generate qualified prospects and new business
Synchronise your selling tactics with your customer's buying cycle
Motivate prospects to take action by helping them see themselves solving their own problems by using your product or service
Sieze control of the situation and make the sale yourself, even when your competitor was there first.
Close with confidence without using high pressure.
How to identify your customer's real needs and use listening as a powerful selling tool.
How to tailor every sale you make to one specific client
How to earn and maintain your credibility
How to use Miller Heiman personal workshops to identify your strengths and weaknesses and make the necessary changes
have a powerful search facility for finding books on sales jobs and selling techniques and on a number of titles you can also view selected excerpts to give you a feel of the writer's style and approach to the subject. 
(Situation Problem Implication Need- payoff)
