When customer referrals start flooding in, it’s a surefire sign that your startup has made it. Referrals signal happy clients, market traction and increased revenue.

Unfortunately, when selling to highly competitive or secretive industries -- such as sports, entertainment, investment banking, healthcare and others -- customer referrals can be hard to come by. However, that doesn’t make your company second-rate by any measure.

It is just that these organizations tend to be incredibly protective of their brands and services, making it challenging for companies to cut through the red tape and get approved as an outside vendor. And even if you are able to land a deal with the business, actually getting them to allow you to publicly attach their high-profile logo or brand name to your company is difficulty. In their minds, revealing their “secret weapons” would either compromise their competitive advantage or make them vulnerable to outside threats.

Related: Potential Referrals Are All Around You. Pay Attention.

So how do you survive (and grow) when your clientele consists of highly secretive organizations armed with nondisclosure agreements?

Luckily, there are a few ways to work around all of that. Here are three suggestions:

1. Hire insiders.

Bring in industry insiders who can speak on your behalf and have them become your brand advocates. Start by connecting with people who either used to work in the industry (and have a good reputation) or who have a lot of connections. Maybe you know someone who knows someone who knows someone else – "six degrees of separation” style.

2. Refer them to the next best thing.

Potential clients will often ask about your client list or want to speak with referrals before signing on the dotted line. But when your client base wants to remain anonymous, this puts you in a tough spot.

Sometimes, you’ll simply have to explain that you can’t divulge that information and offer compelling facts and statistics about their sector instead. But most of the time, you can find a client willing to speak on your behalf, even if the company isn’t in the same sector.

For example, if you’re trying to sell to an NFL team, but no other NFL team will talk, refer the client to the next best thing: a college football team willing to share its experiences. That way, potential customers can gain some assurance and insight without stepping on other clients’ toes.

Related: The Tricks to Getting 10 Times More Referrals From Your Network

3. Plan for the long term but act in the short term.

Whether your product or service is new to the market or already mainstream, it’s always important to think about the future. Rather than sign clients to multi-year contracts in hopes of making your immediate future a little more secure, think in the short term to get ahead later on.

One-year contracts are more appealing to new clients and give you the flexibility to adjust contract terms, raise prices and make deals as your company’s market value increases. Offering short-term contracts puts the negotiating power back in your hands.

When working in highly competitive or secretive industries, you can’t rely on word-of-mouth marketing to expand your client base. But you can build opportunities for client referrals, logo rights exchanges and customer satisfaction stories into your normal business practices. It may take a little extra work but once potential clients discover why your clients aren’t talking, they’ll be hooked.

Related: How to Increase Your Customer Referrals